Use the pinned references and README validation summary when assessing compatibility. The machine-readable audit records additional boundary probes in reference_update_20261019.json. These probes include unsupported syntax and are separate from strict parity.
The reference accepts a variable or variable-led concatenation as the command clause. RexxAE currently requires a quoted-literal-led combined clause:
LET command = 'cell.get A1'
ADDRESS APP command
/* Currently rejected by RexxAE. Shared form: */
ADDRESS APP 'cell.get A1'Implementing variable-led clauses must preserve the selected environment, RC/RESULT/ERRORTEXT replies, budgeted stepping and host vetoes. ADDRESS remains an application request, with no implicit shell or extra authority.
Use ordinary CALL for expression arguments, then copy RESULT:
CALL pair 'a', 'b'
LET result = RESULT
EXIT
pair: PROCEDURE
ARG p,q
RETURN p || qRexxAE supports assigned CALL only with simple blank-separated arguments.
With those, LET x = CALL f ... gives f's RETURN value on both engines
(RexxJS 5d96050). For the equivalent LET result = CALL pair 'a', 'b', the
audited reference returns 'a',b rather than ab. Nested calls
and arithmetic expose further parser differences. Extending this form needs
an explicit reference-semantics decision; the audit records these outputs
without treating them as desired behavior.
Parenthesized ADDRESS is also unresolved: RexxAE reports an error while the reference silently ignores the audited form. It is not supported shared syntax.
See README coverage for missing language features, function policy for builtin restrictions, and known differences for deliberately distinct results. Passing boundary probes should enter strict/native fixtures when promoted into supported coverage; mismatches must not be counted as parity.
The dated audit preserves upstream commit analysis, spreadsheet observations and the original implementation plan.