SAS has two types of transport files and there is not clear way to tell which style is being talked about if just the word "transport" is used.
There is the original published format for datasets that is generated by the XPORT libname engine. That is often called the V5 transport file format since it only supports the 8 character limit for names and 200 length limit for character variables that was the SAS standard through version 6. The have also made a new version of that file format that supports longer names and longer character variables. To make that you need to use the macros that they have released instead of the XPORT libname engine. I believe that the code and the header rows that it generates in the file might talk about V8 or V9 format, but in reality all it is supporting is the longer variable names and character variable lengths that were introduced in SAS version 7. So personally I would call that the V7 format transport file. The change for version 9 might be that format names can be longer than 8 characters.
But you can also make portable files using PROC CPORT and read them with PROC CIMPORT. These files are a totally different format that is NOT published and can change with each release. In general you can read "CPORT" files make with older versions of SAS, but not those made by a newer version than you are running. CPORT files can hold other SAS objects (like catalogs) in addition to datasets.
