> I slept on the problem a bit--good thing that I'm old; I like to > sleep--and think that I've got it sussed out.
:) > Tape appears to consist of 4101 byte blocks, each with a "/02CMSx" > header; the first one seems to be "CMSF" with the intervening ones being > "CMSV" and then a final 87 byte block starting with "/02CMSN" and with > what appears to be file metadata, including the file name. The body of > the 4K+ blocks appears to be 80 character card images. Last block of > each file seems to be padded with nulls. Starting on pdf page 135 here is a description of the FST data structures from circa 1986: https://bitsavers.org/pdf/ibm/370/VM_SP/Release_5_Dec86/LY24-5221-2_VM_SP_Release_5_Data_Areas_and_Control_Block_Logic_Volume_2_CMS_Dec1986.pdf Might help sort the CMSN block. De
