TFORMer functions accepting filenames like TFormer_SetRepositoryName, TFormer_SetDataFileXML, ... are accepting the following parameters: Plain file names (*.tfr, *.tff, *.xml) Zipped files (zipped *.tfr, zipped *.tff, ...) BASE64 encoded strings containing plain or zip files (in such a case the string must start with "BASE64:" - without apostrophes) Usually all TFORMer functions accepting files are trying to determine if it is a zip-file automatically (a BASE64 encoded file is determined by the BASE64: prefix). When TFORMer detects a zip-file it is unzipped automatically to the temp-directory of the current user. This automatic unzipping requires TFORMer to clean up such temporary files after the function call ends. If you want to avoid the per-function unzipping and deleting, then implement the unzipping functionality yourself by the TecUnzipper-functions.