They are often used to move data from a newer version of SPSS to a much older version, which might not be able to read a modern .sav file. .por vs. .sav: Key Differences .sav (Binary) .por (Portable) Format ASCII/Text Speed Fast read/write Slower read/write File Size Portability High (within modern systems) Maximum (across old/new/different systems) Variable Names Long/Unicode supported Limited (usually 8 characters) How to Create a Portable File in SPSS
Then variable definitions:
When you run SPSS from a portable drive: ibm spss portable