XML vs Markdown for agent instructions

Markdown sections (`## Role`, `## Rules`) are human-friendly and work well in repos and RAG corpora. Models parse headings reliably when chunks align with section boundaries.

XML tags (`<role>`, `<rules>`) give explicit boundaries for parsers and some enterprise agent frameworks. They reduce ambiguity when sections nest or when automated tools extract blocks.

Which to choose

Use Markdown when developers edit in Git and RAG chunking follows headings. Use XML when your runtime expects tagged blocks or you export to systems that validate schema.

aiStructEdit edits one structured document and exports both — same content, different serializers — so you do not maintain two sources.