This is a very simple environment to edit and run "XOP macros".
An XOP macro is a bunch of IDL instructions that are executed line per line.
The code cannot be pre-compiled (in IDL terms). Code lines are executed one by one. However, a mechanism has been defined for creating IF and FOR blocks. These blocks are compacted into a single IDL command line before being executed. The "compacted" code can be previewed by clicking on the "Compact" button.
Limitations:
No IDL compilation "on the fly" allowed using XOP with embedded IDL
Macros are very difficult to debug.
Bugs:
There are sometimes internal conflicts with the variables producing unexpected results.