os-release is documented like this:

"The basic file format of os-release is a newline-separated list of environment-like shell-compatible variable assignments. It is possible to source the configuration from shell scripts, however, beyond mere variable assignments no shell features are supported"

This doesn't say whether double-quoted and/or single-quoted strings are supported, whether the usual set of '\' escapes inside double-quoted strings are supported, or whether this sort of thing (which would work in a shell) works:

    # expands to: O'Reilly "Undocumentable" Linux
    PRETTY_NAME="O'Reilly "'"Undocumentable" Linux'

My guess would be that "", '' and \ escapes should work, but multiple concatenated quoted strings don't/shouldn't.

It'd also be nice if shell-style comments (unquoted #) were supported, as they are in many configuration files (even those with ad-hoc formats).