# Investigate Unicode and bidirectional source rules

Type: research
Status: resolved
Parent: [Find the ASPL MVP specification](../map.md)

## Question

Which Unicode normalization, identifier, bidirectional-text, and confusable-character rules should an Arabic-first source language consider, according to Unicode standards and relevant language specifications, before ASPL chooses its MVP lexer and diagnostic policy?

## Answer

Pin Unicode 17.0 and decode `.aspl` files as strict UTF-8. Use a documented Arabic-or-Latin profile of `XID_Start` and `XID_Continue`, add `_`, compare case-sensitive identifiers after NFC normalization, retain combining marks, and reject mixed-script names, non-ASCII digits, default-ignorable characters, and characters outside the UTS #39 General Security Profile. Use direction-aware UTS #39 confusable checks only for warnings, never for name equality. Parse source in logical order; admit LRM and RLM only as semantically invisible token-boundary controls, render all bidi controls visibly in diagnostics, and require the website editor to follow UTS #55 token-atom ordering for RTL and LTR display.

See [Unicode and bidirectional source rules for the ASPL MVP](../research/04-unicode-source-rules.md) for the cited rationale, diagnostic contract, and conformance cases.