Pocsag encryption

Pocsag encryption

Summary

Prism-IPX introduces new products for encrypting and transporting paging messages which can be sent to compatible paging terminal switches or encoder systems that are capable of encoding encrypted messages. Install at remote sites where messages originate and send to centrally located Prism paging systems for broadcast over the paging transmitters.

The Paging Encryption Server PES is used in medium to large systems with up toenabled pagers and is designed to be installed in paging systems for customers that require their data remain within their network or premises.

pocsag encryption

Other encryption protocols will be considered based on customer interest. The Paging Encryption Processor PEP is a basic paging message encryption processor designed for small paging system requirements. Uses TNPP routing to receive paging messages from a compatible external paging terminal, and to send encrypted messages back to a compatible paging encoder capable of encoding the data.

The Paging Encryption Server is designed for medium to heavy use messaging systems. The PES combines a simple web-based management system with a powerful encryption server. The PES web interface offers multiple levels of user access with different permissions.

This allows for the control and security of encryption keys within the system. Paging Encryption Servers. Toggle Sliding Bar Area. IWCE APCO The name is an acronym of the P ost O ffice C ode S tandardisation A dvisory G roup, the name of the group that developed the code under the chairmanship of the British Post Office that used to operate most telecommunications in Britain before privatization.

In the s new paging codes were developed that offered higher data transmission rates and other advanced features such as European and Network roaming. In an international group of engineers began to meet to explore the possibility of developing a new code for wide area paging; paging networks covering regions of entire countries.

Tridgell and were attended by representatives of British, European, and Japanese pager manufacturers [1]. The high frequency represents a 0 and the low frequency a 1. Some jurisdictions require that all systems move to a "narrowband" configuration, using Transmission use bit blocks called codewords.

Each codeword carries 21 bits of information bits 31 through 1110 bits of error-correcting code bits 10 through 1and an even parity bit bit 0.

Bits 31 through 1 are a binary BCH code 31, The error-correcting code has a 6-bit Hamming distance : each bit codeword differs from every other codeword in at least 6 bits. Consequently, the code can detect and correct up to 2 errors in a codeword. The generating polynomial g x for the BCH 31, 21 code is: [4]. The codewords are either address or data, which is indicated by the first bit transmitted, bit Each data codeword carries 20 bits of data bits 30 through to Codewords are transmitted in batches that consist of a sync codeword, defined in the standard as 0x7CDD8, followed by 16 payload codewords that are either address or data.

Any unused codewords are filled with the idle value of 0x7A89C Although the address also referred to as a RIC - Radio Identity Code or CAP code - Channel Access Protocol code [5] is transmitted as 18 bits the actual address is bits long: the remaining three bits are derived from which of the 8 pairs of codewords in the batch the address is sent in.

This strategy allows the receiver to turn off for a considerable percentage of the time as it only needs to listen to the pair that applies to it, thus saving a significant amount of battery power. Before a burst of data there will always be a preamble of at least bits of data containing alternating 1s and 0s, allowing the receiver to synchronize itself to the signal, and is another mechanism that enables the receiver to be turned off for a large percentage of the time.

A message will start with an address codeword followed by a number of data codewords and will continue until another address, a sync, or an idle codeword is sent. When the data bits are extracted they will be in one of two formats. There are two message coding formats for the data messages.

The most significant nibble bits 30,29,28,27 is the leftmost or most significant of a BCD coded numeric datum.

BCD messages are space padded with trailing 0xC's to fill the codeword.

POCSAG VHF/UHF Transmitter

There is no POCSAG specified restriction on message length, but particular pagers of course have a fixed number of characters in their display. Alphanumeric messages are encoded in 7-bit ASCII characters packed into the 20 bit data area of a message codeword bits Since three seven bit characters are 21 rather than 20 bits and the designers of the standard did not want to waste transmission time, they chose to pack the first 20 bits of an ASCII message into the first code word, the next 20 bits of a message into the next codeword and so forth.

What this means that a 7-bit ASCII character of a message that falls on a boundary can and will be split between two code words, and that the alignment of character boundaries in a particular alpha message code word depends on which code word it is of a message.

The side benefit of this is a slightly increased error-correcting code reliability for messages that span more than one POCSAG packet. The frequency The frequency is still reserved for paging but is not used. In Italythe These frequencies are often used for on-site hospital paging systems, including voice paging. It appears that US-specification paging systems operating on Slashdot is powered by your submissionsso send in your scoop.

Comparable equipment has traditionally cost in the 10s of thousands. Only in the last two or three years has it been in the home hobbyist range. Granted its not cheap, but its about the same as a good gaming rig. And its far less than car or shooting enthusiasts tend to spend.

The receivers range from a hundred to almost five hundred depending on what you need. Same API to control all of them though. If you want to mess with the fpga instead of doing it all on the PC you probably want the slightly cheaper motherboard so you can use the free xilinx webpack ise instead of the crazy expensive one. Slapping an fpga and highspeed ADC onto a custom PCB is easy enough, you can get such things from knjn prebuilt, but you really need gigabit ethernet or faster to do software processing on significant bandwidth and those sorts of interfaces tend to need five and six layer PCBs which aren't DIY and jack up the price.

Perhaps the USB3 interfaces will be more hobby friendly. You still need a software controlled wideband receiver too, maybe heathkit will step up on that one. All in all, the USRP is reasonable, though its been getting more expensive due to more features, and NI buying them might be involved too, NI doesn't tend to make cheap stuff. A local news service would. Typically the encrypted channels on many city police systems are the "command nets. The use of encrypted systems by "officers" generally would be limited to ERT A.

Besides most criminals could not afford the current scanners that can grab the clear transmissions now anyway. FUNcube Dongle [funcubedongle.

Emergency pager system 'should be encrypted'

Quoth shoc. No drivers required! As a ham radio operator, I know a few guys that spend 2 to 3 grand on P25 Mototola radios. I can picture a couple of them now, reading this paper over very carefully :. I would have thought that any wireless communication device can be easily DoSed by a normal jammer. No specific knowledge of the protocol needed. In other words, they may not be able to keep a secret because the other stuff doesn't understand HOW to.

As to how effective their security would be otherwise, I couldn't say, although apparently authentication is a major problem that would need attent.

pocsag encryption

Other parts of the article talks about security features being disabled because of interoperability. As I read the part of the article I quoted, there simply isn't any specification in the protocol to authenticate inhibit command, so this specific problem is not because of interoperability.

SDR As A Police And Fire Radio Scanner

The interoperability referred to is whether the inhibit request is sent encrypted or in the clear, not whether or not it had authentication. If you have the wrong crypto type, you can just fall back into clear mode for "interoperability".

APCO 25 doesn't seem to be very well thought through. Easily jammed at multiple levels and vulnerable in many ways.Posted October 23, Victoria's emergency services pager network should be encrypted, according to a former Country Fire Authority CFA volunteer and radio technician. Pager messages sent over the Emergency Alerting System EAS can include personal and sensitive information about ambulance patients. Ian Gilchrist, who worked for the navy as a radio technician, built a system which decodes and archives EAS messages but decommissioned it due to legal concerns.

Labor has promised to upgrade the regional police radio network if it wins the Victorian election, but neither party has committed to encrypting the EAS. Mr Gilchrist said he "spent literally hundreds of hours" building the system, which provided many advantages to emergency volunteers.

However often brigades are called upon to help neighbouring brigades with large fires, so it is advantageous to receive messages meant for those brigades as well.

After running the system for a few years he received an email from a man in Queensland, warning him of potential legal problems. Mr Gilchrist contacted his local police, the Justice Department, the Federal Police and the Australian Communications and Media Authority to try and establish what the law was, but had little success.

President of Liberty Victoria Jane Dixon said making emergency services messages available to a third person could contravene state and federal laws.

While Mr Gilchrist eventually turned off his system, he was not sure that he ever would have run into serious legal trouble. Ambulance Victoria chief executive Greg Sassella said individuals had been scanning the emergency services' analogue radio and pager networks "for decades".

While enjoying the technical challenge of decoding the EAS, Mr Gilchrist believes the messages should be encrypted, especially those sent to ambulance officers. He said police in rural areas do licence checks over the analogue radio network, which can be listened to by anyone with a police scanner and could be used for identity theft.

Either way, securing the paging network would likely cost even more due to the number of receivers involved. Topics: emergency-planninghealth-administrationwireless-communicationpoliceinternet-technologyinformation-technologygisborne Contact Simon Leo Brown. More stories from Victoria. If you have inside knowledge of a topic in the news, contact the ABC.

ABC teams share the story behind the story and insights into the making of digital, TV and radio content. Read about our editorial guiding principles and the standards ABC journalists and content makers follow. Learn more. If you have to visit the supermarket this Easter, here's a few tips to avoid getting coronavirus.

With gyms and pools closed, some of us are struggling to stay fit. Here's how to make sure you're getting enough exercise. By China correspondent Bill Birtles. It has taken 76 days, but the city where the devastating coronavirus pandemic all started is finally ending its lockdown. But this is not a return to normal and residents aren't exactly celebrating just yet. By Peter Marsh and Emily Olson. Breaking news The Federal Government has been negotiating access to those countries.

Senator Payne says the flights are expected to take off over the next week.

Pager Options

ABC Radio Melbourne. Photo: Pager messages sent over the EAS can include personal information about ambulance patients. Supplied: Ian Gilchrist.The Digital Alert Viewer Paging is designed to perform the function of monitoring for alert messages and displaying a list of active alerts on attached digital televisions, via an HDMI interface.

Click here for more information. The Mobile Alert Response System is a state-of-art embedded system that supports the management of active alerts for mobile response teams. We provide wide range of customised solutions for Paging System to meet specific customer requirements.

Br is an alphanumeric POCSAG pager that allow users to receive messages broadcast over on-site or nation wide paging system. Get a quote. It is both an Inclinometer and Goniometer. Designed by Physiotherapists for Physiotherapists. The Maxpage terminal is a feature-rich paging solution equipped to meet almost any one-way communication need. The Maxpage can be utilised in various ways, such as simply sending a pre-set message to a single pager or group of pagers.

This done by pressing a button on the Maxpage unit itself.

How to Decode POCSAG & FLEX using an RTL-SDR Dongle

The Daviscomms Telemetry Messaging Receiver is a one-way paging device with output ports which is used as a low cost device to receive data or control equipment. This module is suitable for wireless control systems and wireless automation devices and has been used around the world for applications like —.

Daviscomms UK is serving Worldwide Clients.The project, which results in the crystal clear audio reception heard after the break, uses a whole lists of packages on a Windows box to access the emergency bands.

In this case the dongle is a Newsky TV28T v2 module that he picked up for a few bucks. We wonder how many areas this will work for. It was our understanding that law enforcement was moving to encrypted communications systems. This is really amazing, if your area is on a P25 digital trunk system. Having a 2nd tuner dedicated for the control frequency really helps this setup in terms of responsiveness. Pretty well all of the systems in major cities in Australia are now or will be soon encrypted, so I suppose enjoy it while it lasts.

Any agency in Louisiana can talk to any other agency in the state and other states if they are a member of LWIN. That depends on if the radios have all that programmed in. Only city units have city talkgroups, etc even though the radios are dual band or quad band radios they waste a lot of money on them by not setting them up to be compatable and this is largely due to Shreveport Communications owned by the god fearing Faith family being greedy asswipes.

They talked Shrevport and caddo parish in to renewing their MHz analog license a couple years ago instead of letting them go onto LWIN becaus ethey would have lost sole business with the parish. Actually my example is Australia. In Great Britain the Airwave project was created in a public-private partnership which has the overseeing entity Airwave Solutions making money hand over fist every time anyone in the country hits the PTT button.

In Australia the states have taken a dim view of going to the extent to encrypt communications and then route it through infrastructure owned by a private company, so instead they setup their own. This post was worth reading just to find out about SDR — I guess its time to break out the tuner again and try it. In the video, is the channel automatically going to the signal with the peak level, or is the user manually switching channels?

Per the article, the channel switching is being done automatically… the channel it keeps going back to is the control channel and it reads that to determine which active channel to switch to for the parts of the conversations. Discones work really well over a wide frequency range. Not as good as a specific antenna for a specific frequency, but a great general purpose wideband receiving aerial. Years back I had rabbit ears hooked to a WinTV tuner card and found some mode in the software to let me tune by frequency.

pocsag encryption

Is it possible to listen to aircraft with this? There is an approach right over my house and it might be cool sometimes.

I use one of these to listen to the air band all the time. Air traffic including approach channels and local airport information are all broadcast in analogue. Spikes every 28kHz or so across the whole 2MHz slice… and the thing gets hot after a while. That vastly improved things as far the noise floor, but the spikes are still there not to mention the huge LO spike in the middle.

Plus, if the dongle is in the box, I can provide it with a better ground than going though the guts of the computer through the USB. I would much rather have a DIP-4 package. But Mouser stopped stocking them. You sure those spikes are noise and not a function of the poor hardware dongle itself?

I get the same thing when tuning in certain frequencies and I highly doubt the government would tolerate this kind of interference near airtraffic bands where I experience it. I am about to try a different dongle because of this. Also I suggest try the SMD route. You may like it. It really is quite easy and the only special tool you need is a set of tweezers.

Even a standard soldering iron is fine for SMD work, though the finer the tip the easier it is. My results are similar to yours. I solved this by isolating the power from USB and also putting the unit in a shielded enclosure.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Because of the breadth of available code and the time spent converting and connecting them and testing the program for performance,The work is time consuming.

If you are interested in encouraging us to complete our program For this purpose you can send the few amount of bitcoin to the following address.

Developers or enthusiasts can use it at a regular fee. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Sign up. Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again. Latest commit. Latest commit 05e3b4a Apr 8, How to help improve the program If you are interested in encouraging us to complete our program For this purpose you can send the few amount of bitcoin to the following address.

You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Mar 13, Delete rtlsdr. Apr 7, Apr 8, ADS-B added. Apr 6,


All messages are secured from the dispatcher to the pager endto-end which means that messages can only be read by authorised pagers. The bit protection key delivers one of the highest levels of security currently available. Instead of each RIC address being notified one at a time, the alert text is sent simultaneously to all needed users.

Less data allows for faster transmission time. Hybrid combines the reliability of a paging alert with the benefits of commercial mobile telecommunications networks.

Only the fastest, of the alert messages, is displayed on the pager screen and any other is suppressed. Bluetooth technology makes it possible to connect the s. QUAD with a compatible smartphone and ultimately with various s.

ONE software solutions from Swissphone. In idle state, the pager is set in a sleep mode and the display is switched off. At all times, the pager remains active and ready to receive alarm signals. GLOB is a replace text pattern option that allows you to either suppress text or replace it with a fixed text. With this software option the s. QUAD terminal can receive voice calls and text messages from two different networks.

This two-in-one option perfectly supports the migration from analog to digital. The s. Even in the most sensitive zones, the s. This device uses a bar graph to display the signal strength, and the higher the value, the better the reception in the respective location.

When used in conjunction with a return channel, RSSI readings can be sent back to the system for quality control purposes. Do you have questions? You can use our contact form to send us your questions and suggestions.Ready-to-use when delivered. Individual programming using our programming form is included. No additional costs for programming or frequency change within the selected frequency band. Frequency, baud rate and capcodes can be changed manually by the user. This makes changing of programming perfectly easy, e.

Immediately ready for use. The DME comes fully programmed for digital alerting according to your individual requirements in the programming form. No further costs for programming and quartz! The DME comes with charging station and fully programmed for digital alerting according to your individual requirements in the programming form. Alphapoc dual-frequency operation is available and tested!

Following in-depth development and implementation, the advanced feature is now available: dual-frequency operation on two parallel operating channels in the range MHz. The complete menu is in German! The Lifestyle - Pager. The ideal second device for office work or readiness The lifestyle pager as a second device for office life or readiness!

Paging Encryption Servers

Messages and symbols are displayed in standard mode with up to 8 lines and max. The background of the display is RIC-dependent in 7 colors illuminated. OTA programming functions included. E-Mail: alphapoc alphapoc-europe. Find us. Find us at. My Account. Sign in. Mobile view. Your basket is empty. Categories pager. Promotional product. Product search. Our European Logistic-Partner:. Old price VAT, plus delivery.

Contact information.The PriMega Message Gateway is the central management point of a system. All calls, messages, alarms, and notifications are processed by the PriMega and logged for usage and diagnostic reports. The PriMega manages a paging network from the message input using telephone and data lines to the data output. The Prism-IPX ipBSC Model Version 2 is a network base station controller designed for use with the Prism-IPX PriMega series of text message handling systems for message transmission over single transmitter or multiple transmitter radio simulcast networks used primarily for paging technology.

Choose from 1, 3 or up to 20 ports, our IP controlled AB switches are widely used for switching connections between redundant systems and for enabling or disabling remote equipment. Commands sent from Prism products cause the device to switch upon demand.

pocsag encryption

Install at remote sites where messages originate and send to centrally located Prism paging systems for broadcast over the paging transmitters. The IPT is a versatile small footprint Linux based product used for small paging systems and for converting data protocols for messaging systems. The transmitter can be used as a standalone unit for covering a campus or building, or as a part of a large wide area network with almost any paging terminal vendor. The transmitter can also be seamlessly installed in place of other transmitter brands in an existing UHF paging network.

Paging Message Logging software collects data decoded off-the-air and sends the data to the logging server. Logs can be used to prove messages were actual transmitted and were capable of being received without error.

PriMega Message Gateway. Paging Encryption Servers. Message Logging Systems. PFC-1 Siren Controller. Toggle Sliding Bar Area. IWCE APCO All messages are secured from the dispatcher to the pager endto-end which means that messages can only be read by authorised pagers. The bit protection key delivers one of the highest levels of security currently available.

pocsag encryption

Instead of each RIC address being notified one at a time, the alert text is sent simultaneously to all needed users. Less data allows for faster transmission time. Hybrid combines the reliability of a paging alert with the benefits of commercial mobile telecommunications networks.

Only the fastest, of the alert messages, is displayed on the pager screen and any other is suppressed. Bluetooth technology makes it possible to connect the s. QUAD with a compatible smartphone and ultimately with various s. ONE software solutions from Swissphone. In idle state, the pager is set in a sleep mode and the display is switched off. At all times, the pager remains active and ready to receive alarm signals.

GLOB is a replace text pattern option that allows you to either suppress text or replace it with a fixed text. With this software option the s. QUAD terminal can receive voice calls and text messages from two different networks. This two-in-one option perfectly supports the migration from analog to digital.

The s. Even in the most sensitive zones, the s. This device uses a bar graph to display the signal strength, and the higher the value, the better the reception in the respective location. When used in conjunction with a return channel, RSSI readings can be sent back to the system for quality control purposes.

Do you have questions? You can use our contact form to send us your questions and suggestions. Sign up for our newsletter. We use cookies in order to design our website in the most optimal way for you and to be able to continuously improve it. We also share information about your use of our website with our social media partners, advertisers and analysts.

By using this website, you consent to the use of cookies.Field of operation: silent alert, e. The device is driven by a Lithium-battery. Charge status is indicated by a LED on the device or via radio transmission the the dispatch center. Highly reliable due to repeated transmission. All parameters can be set directly on the keypad. Furthermore, the PS can be controlled comfortably using the integrated USB-interface on a windows computer. The device features and configuration can be displayed and programmed using a user-friendly software-interface.

The modulation connector offers control signals for special metering and testing setups. The PS is the ideal tool for maintenancing and testing pager devices following e. Detaillled product information can be obtained in our download-section!

The siren is switched via a power relay. Additional information can be obtained via our downloads - section! Improved interpreation of FMS-broadcasts. DSP interpretates the radio transmission and the emitter forwards the cleared signal to the DGA unit. Extremely fast alert transmission and active feedback of available personnel lead to an effective ressource planning enabling units to the fastest first response.

Often, other systems can only achieve this with higher costs and an individual solution not being compatible with other systems. Loud alerting, high-quality clear voice instructions and MP3-Signal tones can be used for various operational scenarios. Detailled product information can be found in our Downloads! Home News Services Products. Large display. NRS Sending- and receiving devices for emergency calls and remote controls.

Alarm-devices including software-support for BOS-Alertsystems. Hands-free kits for radio devices. Mobile pager test device PS The PS testing device is a handheld device and is intended to use for testing mobile pagers. Option DSP interpreter and emitter D-Sub-connector for PC and pol. D-Sub-connector for radio unit incl. The digital alert system SIRIUS is specially designed for all purposes in alerting for emergency services and other aid and relief organisations as well as industrial customers which are dependant on fast and effective alerting of technical staff.

How to Decode POCSAG & FLEX using an RTL-SDR Dongle

The digital alert emitter DAG is based on a modern client-server architecture and enables dispatcher units to activate and emit alerts The digital alert relay DAU is characterized by the consequent integration of modern technical interfaces IP, ISDN, V.

Other features like repeater-functions even to other networkssequential broadcasting using different baud-rates for compatibilty to other systems are possible. Main parameters of the DAU unit are set by over-the-air interface. Bug-proof using bit encryption The over-the-air interface offers a reliable redundancy using two seperate transmission units W incl. Integrated backup power supply garantuees a lossless alerting in case of power breakdown.

Frequent polling of malfunction sensors provide provide constant information about the system state. In the following you will see an overview of our pager product line. Product information for other pagers is available at our download-section. Oelmann Elektronik offers several different digital interpreter-systems. In this section, you will find an overview on our products:.You seem to have CSS turned off.

Please don't fill out this field. Please respect the law in your country concerning the capturing of radio-transmissions. OpenPoc Web Site.

pocsag encryption

Do you have a GitHub project? Now you can sync your releases automatically with SourceForge and take advantage of both platforms. Please provide the ad click URL, if possible:.

Help Create Join Login. Operations Management. IT Management. Project Management. Services Business VoIP. Resources Blog Articles Deals. Menu Help Create Join Login. OpenPoc Status: Alpha. Add a Review. Get project updates, sponsored content from our select partners, and more. Full Name. Phone Number. Job Title. Company Size Company Size: 1 - 25 26 - 99 - - 1, - 4, 5, - 9, 10, - 19, 20, or More.

Get notifications on updates for this project. Get the SourceForge newsletter. JavaScript is required for this form. No, thanks.A campaign that looks perfect in Gmail might look different in Outlook 2002. In your campaign's Inbox Preview, we'll let you know which email clients are the most popular for your list. Before you send your campaign, use Inbox Preview to avoid unpleasant surprises, and adapt your designs to work best with your list's top email clients.

Inbox Preview uses a token system. Each time you successfully create or update a preview, the cost is one token. For example, if you run an Inbox Preview for Outlook 2011, Gmail, and Apple Mail 7, the cost is three tokens.

Each billing cycle, MailChimp Pro accounts receive 1,000 free tokens, and Monthly Plan users receive 25 free tokens. Unused tokens expire at the end of each billing cycle and the free token balance resets on the billing cycle renewal date.

Users with valid billing information can purchase additional tokens as needed. Run an update to refresh Inbox Previews of your draft campaign in various email clients.

Each email client you update will cost one token per preview. Paid users can log in for email or chat support. Paid users can log in to MailChimp on a web browser and open the Knowledge Base to contact our Support team. Learn more about our support options. In this article, you'll learn how to use Inbox Preview. Note We're releasing a new Campaign Builder, so some of the steps in this article may differ from what you see in your account. Yes No It was easy to find what I was looking for.

I could easily scan a help article to find the information I needed. The help articles are easy to read. The help articles helped me resolve my issue. MailChimp is easy to use.

I just love MailChimp. The help articles don't make sense. I wish there was a video that showed me how to do this. What I'm trying to do in MailChimp doesn't work the way I think it should. It was hard to find what I was looking for. I never found what I was looking for at all.

POCSAG Paging

I have to contact Support to resolve my issue (for example, an account or billing problem). Thanks for submitting your feedback. At this time, we are unable to reply to any responses, but we'll use this information to keep the site up-to-date. Sorry, we were unable to submit your feedback. MailChimp Resource guides KB Blog Contact Back to top Yes No Awesome.

Can you tell us more about your experience today. It was easy to find what I was looking for. Sorry we couldn't be more help. Can you tell us about your experience today. Different email programs display your HTML email differently, so it's important to preview and test your campaign content before you send to your subscribers.

Testing time decreases once you settle on a layout that works for you, but we recommend spending at least an hour to test new templates.


thoughts on “Pocsag encryption
Leave a Reply

Your email address will not be published. Required fields are marked *