Is there a variable length field in TIBCO ActiveMatrix BusinessWorks™ Plug-in for Data Conversion?
For example, to accommodate binary data which could have from 0 to 2000 bytes.

In Cobol., every field corresponds to an area allocated in memory by specifying a size in number of bytes. A "variable record" definition is not applicable. To produce variable length binary data, we can trim the binary data after rendering when using a data conversion plugin. Or we can use the string-to-base64 function directly in BusinessWorks.