I-Regexp: An Interoperable Regular Expression Format

I-Regexp (RFC 9485) is a proposed standard from the Internet Engineering Task Force (IETF) that defines a limited, portable subset of regular expressions ("regex"). The problem it solves: different programming languages and tools implement regex differently — the same pattern often behaves differently in Python, JavaScript, Perl, Rust, etc. I-Regexp restricts which features can be used (e.g., no lookahead, no backreferences) to guarantee that any I-Regexp pattern will match the same strings on any compliant implementation. This matters for interoperability: if two systems (say, a data validator and a database) need to agree on what a "valid email" or "phone number" looks like, they can both use I-Regexp without mismatches.