the "_t30" could be a test version. IE pl_cashworks_rc2_t5 could mean a test compile of rc2, no such "test" versions would be sent to anyone (unless its like 1 person or something to help you test) and would just be for your own archives (renaming the vmf too so you can go back to previous versions if things go sour)
thats what I take it as anyways, you shouldn't use it in any map you release for play.