xPL Protocol


The XPL language is a simple, small, efficient dialect of PL/I intended mainly for the task of writing compilers. The XPL language was also used for other purposes once it was available. XPL can be compiled easily to most modern machines by a simple compiler. Compiler internals can be written easily in XPL, and the code is easy to read. The PL/I language was designed by an committee in 1964 as a comprehensive language replacing , , and , and meeting all customer and internal needs. These ambitious goals made PL/I complex, hard to implement efficiently, and sometimes surprising when used. XPL is a small dialect of the full language. XPL has one added feature not found in PL/I: a datatype with dynamic lengths. String values live in a separate text-only memory space with automatic of stale values. Much of what a simple compiler does is manipulating input text and output byte streams, so this feature helps simplify XPL-based compilers.

Types of XPL Files

Primary XPL File Association


File Format: .xpl
File Type: LcdStudio Playlist File

An XPL file is a settings file used by the program LcdStudio. It saves a list of XDS design files to be played in an LcdStudio application and is used to display dynamic visualizations from live computer performance data.

Created by: Interscape
File Category: Settings Files
Registry Key: HKEY_CLASSES_ROOT\.xpl

Software Programs That Open The LcdStudio Playlist File:

LCDStudio by Interscape

Compatible with:


Other XPL File Associations


File Format: .xpl
File Type: X-Plane Plug-in File

An XPL file is a plug-in file associated with the flight simulation program X-Plane. A plugin is an executable code that runs inside X-Plane, extending what X-Plane does without the need of having a source code.

Created by: Interscape
File Category: Plugin Files

Software Programs That Open X-Plane Plug-in File Files:

X-Plane by Interscape

Compatible with:



File Format: .xpl
File Type: KaZaa Music File

The XPL file extension is associated with the multimedia software KaZaa. It stores music in an audio format supported by KaZaa.

Created by: Sharman Networks
File Category: Audio Files

Software Programs That Open KaZaa Music File Files:

Kazaa Media Desktop by Sharman Networks

Compatible with:



  • Alexander, W. G. and Wortman, D. B. «Static and Dynamic Charactersistics of XPL Programs.» IEEE Computer November 1975; 41-46.
  • Ancona, Massimo, Dodero, Gabriella, and Durante, Ercole Luigi «Cross software development for microprocessors using a translator writing system» Proceedings of the 4th International Conference on Software Engineering 1979: 399-402.
  • Kamnitzer, S. H. «Bootstrapping XPL from IBM/360 to UNIVAC 1100.» ACM SIGPLAN Notices May 1975: 14-20.
  • Karger, Paul A. «An Implementation of XPL for Multics.» SB thesis. Massachusetts Institute of Technology, 1972.
  • Klumpp, Allan R. «Space Station Flight Software: Hal/S or Ada?» Computer March 1985: 20-28.
  • Leach, Geoffrey and Golde, Helmut. «Bootstrapping XPL to an XDS Sigma 5 Computer.» Software Practice and Experience 3 (1973): 235-244.
  • McKeeman, William M., Horning, James J. and Wortman, David B. A Compiler Generator. Englewood Cliffs, NJ: Prentice-Hall, 1970.
  • McKeeman, W. M., Horning, James J., Nelson, E. C., and Wortman, D. B. «The XPL compiler generator system.» AFIPS Conference Proceedings: 1968 Fall Joint Computer Conference. Washington DC: The Thompson Book Company. 1968: 617-635.
  • Sitton, Gary A., Kendrick, Thomas A., and Carrick, Jr., A. Gil. «The PL/EXUS Language and Virtual Machine» Proceedings of the ACM-IEEE Symposium on High-level-language Computer Architecture Nov, 1973: 124-130.
  • Slimick, John «Current Systems Implementation Languages: One User’s View» Proceedings of the SIGPLAN symposium on Languages for system implementation Oct, 1971: 20-28.
  • Storm, Mark W., and Polk, Jim A. «Usage of an XPL Based Compiler Generator System» Proceedings of the 14th annual ACM Southeast Regional Conference April 1976: 19-26.


  1. Indeed, using a hand-written LALR-like analyzer and a particularly efficient «decomposition» procedure for the produced parsing tables, it was possible to generate a parser for the entire XPL language on a 2 MHz microcomputer which had only 48 kilobytes of internal memory () and only 100 kilobytes of external memory () running under . This version was completed in 1980. Porting to MacOS (9, later X) was subsequently completed.
  2. This version was NOT released to the general community, hence it remains proprietary to its authors, or to their institutions. Repeated requests for an SLR(1) or an LALR(1) distribution of XPL have been ignored by its authors.

XPL File Summary

Most XPL files can be viewed with three known software applications, typically LCDStudio developed by Interscape. It’s main file type association is the LcdStudio Playlist File format, but also includes two other rarely-seen file types.

These files can be categorized as Settings Files, Plugin Files, or Audio Files. In the majority of cases, these files will be Settings Files.

File Extension XPL files have been identified on both desktop and mobile devices.
They are fully or partially supported by Windows, Mac, and Linux.

XPL files have a «Low» Popularity Rating;
this means that they are not present on most devices.

Типы файлов XPL

Ассоциация основного файла XPL


Формат файла: .xpl
Тип файла: LcdStudio Playlist File

Файл XPL представляет собой файл настройки, используемый программой LcdStudio. Это экономит список файлов проекта XDS для воспроизведения в приложении LcdStudio и используется для отображения динамических визуализаций из данных живых производительности компьютера.

Создатель: Interscape
Категория файла: Файлы настроек
Ключ реестра: HKEY_CLASSES_ROOT\.xpl

Программные обеспечения, открывающие LcdStudio Playlist File:

LCDStudio, разработчик — Interscape

Совместимый с:


Ассоциации других файлов XPL


Формат файла: .xpl
Тип файла: X-Plane Plug-in File

Файл XPL представляет собой подключаемый модуль в файл, связанный с программой моделирования полета X-Plane. Плагин представляет собой исполняемый код, который работает в X-Plane, простираясь, что делает X-Plane без необходимости наличия исходного кода.

Создатель: Interscape
Категория файла: Файлы плагинов

Программы, открывающие файлы X-Plane Plug-in File :

X-Plane, разработчик — Interscape

Совместимый с:



Формат файла: .xpl
Тип файла: KaZaa Music File

XPL расширение файла связано с мультимедийным программным обеспечением KaZaa. Он хранит музыку в аудио формате, поддерживаемом KaZaa.

Создатель: Sharman Networks
Категория файла: Аудио файлы

Программы, открывающие файлы KaZaa Music File :

Kazaa Media Desktop, разработчик — Sharman Networks

Совместимый с:



XCOM originally used a now-obsolete bottom-up parse table method called , invented by the XPL team (although the officially released version retains the MSP parser and does not include later-released «peephole optimizations» and additional data types which were developed outside of the original implementation team.) MSP is a generalization of the method invented by for . Simple precedence is itself a generalization of the trivially simple methods that work nicely for expressions like A+B*(C+D)-E. MSP tables include a list of expected triplets of language symbols. This list grows larger as the cube of the grammar size, and becomes quite large for typical full programming languages. XPL-derived compilers were difficult to fit onto minicomputers of the 1970s with limited memories. MSP is also not powerful enough to handle all likely grammars. It is applicable only when the language designer can tweak the language definition to fit MSP’s restrictions, before the language is widely used.

The subsequently changed XCOM and XA to instead use a variant of ‘s bottom-up method. XCOM’s variant is called or SLR. It handles more grammars than MSP but not quite as many grammars as or full . The differences from LR(1) are mostly in the table generator’s algorithms, not in the compile-time parser method. XCOM and XA predate the widespread availability of Unix and its parser generator tool. XA and yacc have similar purposes.

XPL is open source. The System/360 version of XPL was distributed through the IBM users organization. Other groups ported XPL onto many of the larger machines of the 1970s. Various groups extended XPL, or used XPL to implement other moderate-sized languages.

Резюме файла XPL

У нас есть три существующие программные обеспечения, связанные с файлами XPL (как правило это программное обеспечение от Interscape, известное как LCDStudio), и их можно отнести к категории основных типов файлов три. Традиционно эти файлы имеют формат LcdStudio Playlist File .

Чаще всего файлы XPL классифицируют, как Settings Files.
Другие типы файлов также могут относиться к Plugin Files или Audio Files.

Расширение файла XPL поддерживается Windows, Mac и Linux. Данные типы файлов можно найти в основном на настольных компьютерах и некоторых мобильных устройствах.

Рейтинг популярности данных файлов составляет «Низкий» и они обычно не используются.

How to Fix Problems Opening XPL Files

Conduct a Malware Scan of Your XPL File

When an antivirus program is installed on the computer, it is capable of scanning all files on the computer, as well as each file individually. Each file can be scanned by right-clicking the file and choosing the option to scan the file for viruses.

For example, in this picture, we’ve highlighted the my-file.xpl file and right-clicked the file to see the ‘Scan with AVG’ option in the file menu. When this option is selected, AVG Antivirus opens and scans that file for any viruses.


Reinstall LCDStudio

Occasionally you might experience a flawed software installation, which may be due to a problem encountered during the install process. This can prevent your operating system from associating your XPL file with the right software application, affecting what is known as «file extension associations».

Sometimes, simply reinstalling LCDStudio will solve your problem, properly associating your XPL with LCDStudio. Other times, poor software programming on behalf of the software developer can cause problems with file associations, and you may need to contact the developer for further assistance.

Tip: Try upgrading to the latest version of LCDStudio to ensure you have the latest patches and updates installed.

Obtain Another Copy of Your XPL File

Caution: A corrupt file could also be collateral damage of a previous or existing malware infection on your PC, that’s why it is essential that you keep an updated antivirus running on your computer at all times.

Update Your Interscape-Related Hardware Device Drivers

If your XPL file is related to a piece of hardware on your computer, you might need to update your device drivers associated with that hardware in order to open it.

This problem is commonly related to multimedia file types that depend upon a piece of hardware inside of your computer to be successfully opened, such as a sound card or graphics card. For example, if you are trying to open an audio file, but failing to open it, you might need to update your sound card drivers.

Tip: If you are receiving an error message related to a .SYS file when attempting to open your XPL file, it’s likely your problem is related to corrupt or outdated device drivers that need to be updated. Using a driver update software such as DriverDoc can help make this process much easier to complete.

Close Other Applications Running

If all other steps fail, and you are still experiencing problems opening XPL files, it might be due to a lack of available system resources. Some versions of XPL files can require substantial resources (eg. Memory/RAM, processing power) to be properly opened by your computer. This is quite common if your computer hardware is older, and you are using a much newer operating system.

This issue can occur when your computer is having a hard time keeping up because the operating system (and other services running in the background) might be consuming too many resources for your XPL file to open. Try closing all applications on your PC before attempting to open your LcdStudio Playlist File. Freeing up all of the available resources on your computer provides the best environment for attempting to open your XPL file.

Upgrade Your Computer Hardware

If you’ve tried all of the steps above, and your XPL file still won’t open, you might be due for a hardware upgrade. In most cases, even if you have older hardware, processing power is still more than adequate for most user’s applications (unless you do a lot of CPU resource-intensive work such as 3D rendering, financial / scientific modeling, or intensive multimedia work). Therefore, it’s likely that your computer is lacking the necessary amount of memory (more commonly referred to as «RAM», or random access memory) to complete the file opening task.

Try upgrading your memory to see if that helps you open your XPL file. These days, memory upgrades are quite affordable and very easy for even the casual computer user to install in their PC. As a bonus, you’ll probably see a nice performance bump in other tasks carried out on your computer.

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