Finding proper RE syntax or hyperscan documentation about syntax

Hi there

According the hyperscan website hyperscan follows the regular expression syntax of the PCRE library. The regex `\N\.rocks` is causing an error in rspamd which is using hyperscan.

The regex `\N\.rocks` is PCRE compliant according to several check in documentation:
Match any single character that is NOT a line break character (line feed) «\N»
Match the character “.” literally «.»
Match the character string “rocks” literally (case sensitive) «rocks»

But I still get the following error with that RE:
`cannot create tree of regexp when processing '\\N\\.rocks': '\\N' at index 0 not supported.`

Can anyone help with getting the proper syntax for this RE?

Thanks in advance