The ISO people simply assign sequential blocks of numbers for standards.
Five digit numbers are newer standards; they ran out of 4 digit numbers
quite a while ago. There may be no connection at all between 16948, 16949,
16950.. etc.
About 10 years ago when I had a larger expense account I ordered a
directory listing all the ISO standards; it was about 300 pages with about
1 short paragraph per standard. The vast majority cover very specific
product specs say, the physical dimensions of a dry cell battery, or the
data recording formats used by CDROM's
not generalities like ISO 9000 or TS16949. It would
make excellent bedtime reading if you're insomiac.