New comment by newbluemoon on void-packages repository

https://github.com/void-linux/void-packages/pull/34029#issuecomment-967797613

Comment:
`opensp` without `--enable-default-catalog=...` doesn’t find the docbook DTDs in the first place. :(

All distributions I checked use 1.5.2. Maybe they just forgot or didn’t care to update the homepage. ;)

What’s bugging me is why does
`onsgmls -p basic.sgml` work and
`onsgmls -p < basic.sgml` doesn’t.
(`basic.sgml` from `po4a-0.64/f/fmt/sgml/`)

http://openjade.sourceforge.net/doc/nsgmls.htm says
`onsgmls [ option... ] sysid...`

> If no system identifiers are specified, then nsgmls will read the document entity from the standard input. A command line system identifier of - can be used to refer to the standard input. (Normally in a system identifier, <osfd>0 is used to refer to standard input.)


http://openjade.sourceforge.net/doc/sysid.htm says
> There are two kinds of system identifier: formal system identifiers and simple system identifiers. A system identifier that does not start with < will always be interpreted as a simple system identifier. A simple system identifier will always be interpreted either as a filename or as a URL.
...
A system identifier will be interpreted as a formal system identifier if it starts with a < followed by a storage manager name, followed by either > or white-space; otherwise it will be interpreted as a simple system identifier.

But in the above example the `<` is a shell redirection not the start of a formal system identifier so that the file is supposed to be read via stdin. I can only assume that in this case “something” gets lost which is expected to also be fed in via stdin?