The name of a Plugin or other external program to be EXECUTEd; it must reside in the EscapeE plugins folder. E.g.

The contents of the item, including any sub-tags, are written to a temporary file. The name of the temporary file is passed first, before any other parameters supplied by the PARAM attribute. Note that when calling a program, the temporary file must be enclosed in quotes.
If the ENCODING is set to BASE64 and there are no sub-tags then the body text is decoded as base 64, otherwise it is written literally.