An <assign> executable-content element: spec 5.4's deep-path datamodel write.

Two spans that are not the same thing

This struct carries two fields that are easy to confuse and must not be:

• location is the SCXML location attribute's own value - the raw, uncompiled path expression ("foo.bar.baz", "items[0]") an <assign> writes to. It is required (spec 5.4.2, "the value of the 'location' attribute MUST specify a valid location"), so it is @enforce_keys'd; resolving it against the datamodel happens at runtime (Statifier.Machine.Content.Assign), never here - lib/statifier/document.ex's moduledoc forbids Predicator anywhere under lib/statifier/document/.
• node_location is this <assign> element's own Statifier.Parser.Location span in the source document - what every other Document node calls location. It is renamed here specifically so a reader (or a pattern match) can never mistake the path string for the element's span, or vice versa; it is also @enforce_keys'd, since every node has one.

expr is the value source read from the expr attribute - raw, uncompiled predicator source, nilable. text is Statifier.Parser.DOM.text/1's verbatim, untrimmed concatenation of <assign>'s direct text children (verbatim except for the parser's XML 1.0 2.11 line-break fold - ADR-0045), mirroring Statifier.Document.Data.text and Statifier.Document.Content.text); expr and text are both representable on this struct at once, on purpose, so Statifier.Validator.Checks.Assign can report the pair rather than lowering refusing to build one (the same division of labour Statifier.Document.Content's moduledoc states).

Markup children

Spec 5.4.2's "children of <assign>" are not restricted to text: an in-line value specification may be markup, and the corpus writes exactly that (test/scxml_tests/mandatory/invoke/test530_test.exs assigns an <scxml> document to a variable and later passes it as <content expr="Var1">). markup holds a verbatim source slice spanning those children, and markup_location is that slice's own Statifier.Parser.Location span in the parent source - the same two fields, filled by the same Statifier.Lowering.Builders slicing helper, that Statifier.Document.Content carries under ADR-0041 (extended to <assign> by that record's 2026-09-02 Note). No DOM subtree enters this struct, exactly as for <content>.

markup is nil unless <assign> has at least one element child. Unlike text it is not line-break folded: it is opaque source bytes, CR included, at this layer (ADR-0045 decision item 5). expr, text, and markup are all representable at once for the same reason expr and text are - reporting the 5.4.2 mutual-exclusion violation is Statifier.Validator.Checks.Assign's job, not lowering's.