[TUHS] Early non-Unix filesystems?

It's a bit off-topic, but what were non-Unix filesystems like around 1969-1970? The PDP-7 filesystem has i-nodes (file metadata) and filenames separate from the i-nodes. This allows hard links and thus a non-tree structured filesystem. This has always struck me to be one of the most important features of the Unix filesystem: names separated from the rest of the file metadata, and arbitrary hard links so that there is no preferred filename. Were these features in other contemporaneous filesystems? As a side note, the PDP-7 kernel knows about the top-level directory ("dd") but it is agnostic to the concept of "." and "..". What that means is that you can build a filesystem with "." and ".." links and the kernel will deal with them as per all other links. But you can also build a filesystem without "." or ".." and the kernel doesn't care. There's not enough evidence (source code, papers, anecdotes) to confirm or deny the presence of "." in the PDP-7 code that Norman scanned for us. ".." does seem to exist as it is mentioned in one source file, ds.s. It's an intruiging mystery. Cheers, Warren