On most UNIX systems there should be at least ps io vm and sa files. For each group of data files (i.e., files which have the same interval number extension), there should also be an ok file.
You may see the as part be replaced by az. The az indicates that Acquire has compressed the files to reduce file space requirements and data transmission time. When initially created the files are in plain text ASCII format, and their names contain the characters as. Compression is the default option, but you can turn compression off by editing the appropriate line in the APMconfg file, changing CompressFiles=y to CompressFiles=n.