Is there any pattern behind the naming conventions of PostgreSQL Table-Level Locks?

I know that PostgreSQL has 8 level of table locks which are, from least restrictive to most: 1. ACCESS SHARE 2. ROW SHARE 3. ROW EXCLUSIVE 4. SHARE UPDATE EXCLUSIVE 5. SHARE 6. SHARE ROW EXCLUSIVE 7. EXCLUSIVE 8. ACCESS EXCLUSIVE However, I can't really determine any pattern or convention to these names. There are literally 5 words total: ACCESS, SHARE, ROW, EXCLUSIVE, and UPDATE, which are grouped together, seemingly at random, for all 8 levels. I find myself preferring to refer to them as just L1 through L8 rather than their actual names. Are these names just the result of historical conventions that evolved organically in a way which doesn't really have any meaning besides "look at the docs and see what level each is?"