The Apple III Pascal RPS unit usually creates two SOS files for each RPS file; moreover, your SOS file with the .I (index) may be listed as having too many blocks compared to the disk space available. This file functions well, except that you're unable to copy this file to another disk regardless of the amount of room on the destination disk. Attempts to copy this file will give you a "NO ROOM ON VOLUME" error. RPS uses "sparse files", files that are logically larger than the actual number of blocks required to store the information. Since early versions of SOS (pre SOS 1.3) did not know about sparse files, they will copy the files without errors. Another example of a sparse file is a Business BASIC random access file having a record length of 1024, but only using record 1 and record 1000. Logically, this file requires 2002 blocks; actually, only 6 blocks are used. Again, an early version of SOS will copy the file.