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ESL Release Notes

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ESL Release notes

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This Document

This document contains a lot of useful information about this and previous releases of ESL. We have also included a copy of the software licence for your information.

This file contains additional information not covered in the standard documentation and important information you need to know before using ESL.

Please take the time to familiarize yourself with

General Information

Release History (contains information on Bug Fixes and Enhancements)

Known Problems


Please refer to this information before contacting us.

Versions of Windows

ESL 24.10 has been tested with the following versions of Windows;

Windows Server 2019 (64bit)

Windows Server 2016 (64bit)

Windows 10 (32bit)

Windows 10 (64bit)

Windows 11 (*)

If you wish to use any other version of Windows, please contact the ESL Helpdesk.

(* Note: Certain third party applications, e.g. Rumba Desktop, have not been certified for Windows 11. We are aware of issues using non-certified packages, with Windows 11, so recommend checking with the supplier and the ESL Helpdesk prior to migrating to Windows 11.)

Support for 64bit Terminal Emulators

Whilst it not possible to provide a 64bit version of the ESL product, we have managed to compile local applications using 64bit compilers, yet retain the communication with the ESL Runtime. Using this technique, we have delivered a 64bit version of A3270 (i.e. A327064.exe). The A3270 local application is designed to be accessed via the M3270 module, which is significantly different from the ESLCMSRV library, typically used to provide EHLLAPI (i.e. screen scaping) support. To eliminate any Esl App code changes, we have delivered a new include file "ESL64SRV.INC" that provides all the existing screen scraping routines, but uses the local application to marshal communication between 32bit and 64bit processes.

To implement 64bit terminal emulator support, replace the include ESLCMSRV.INC statement within your ESL's application source code with ESL64SRV.INC and re-compile your ESL application.

We do not currently supply a version of ESLFields that supports 64bit terminal emulators; however, it would be possible to create this facility.

Please contact the ESL Helpdesk if your company is considering using a 64bit terminal emulator.

Versions of Visual Studio

Our use of Visual Studio versions follows Microsoft support for them. As Microsoft drops support for a version of Visual Studio, we move to the latest stable release.

This version of ESL has been built using Visual Studio 2022 (VS17.x). If your ESL Application uses any customer written dynamic link libraries (.dlls) that access an ESL function contained in ESLLIB, then these libraries must be re-linked to ensure the correct calling conventions are used.

If you have any specific questions regarding the differences, please do not hesitate to contact us.

Calling Conventions

As of version 14.20, the calling convention used to call external routines has been changed. External subroutine must use the 'C' convention, i.e. calling routine clears the stack. External functions must use the standard convention, as used by System APIs, when the called routine clears the stack. The macros ESLSUBAPI and ESLFNCAPI contained within the supplied source code header EslLib.h, can be used to ensure the correct convention is used. Depending how the entry points have been defined, you may find that the "Linker" decorates the function name with an "@" symbol suffix followed by the number of bytes pushed onto the stack. To remove this decoration, we recommend the use of an "Module Definition File", which explicitly names each entry point that can be called by your ESL application.

ODBC Support

ESL provides access to any database, that has a 32bit ODBC driver, via the ESL Database Services library and the ESLODBC local application. When using a 64bit platform, you must ensure the 32bit version of the ODBC driver is installed, as ESL cannot access the 64bit API's, even though all data sources will be listed regardless of the driver's type. Microsoft recommends that when naming Data Sources, the driver type (i.e. 32bit or 64bit) is included in the name, as there is no facilities to determine whether a specified data source will be accessible. Due to the 32bit EHLLAPI standard used to perform "screen scraping", it is not possible to provide a 64bit version of ESL.

Font Support

As of version 17.10, we have removed the old style bitmap fonts, contained within ESLFONTS font files and replaced them with Open Type fonts contained within four files;




oEslMonoBoldOblique.ttf and


Whilst your applications can still use the old fonts, which date back to 1990, we recommend you improve the quality of the screen presentation by defining fonts, using the "font is" statement, based on the facenames;

o"Esl Mono"

o"Esl Caps"

o"Esl Mono Bold"

o"Esl Mono Bold Oblique" and

o"Esl Mono Oblique"

As of version 21.10, the ESL fonts are installed as part of the installation process. Please see Fonts for more details.