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docs/pre13-low-b.md

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+# Pre13 L-B
+
+This batch completes the planned semantic aliases for internal EROFS NIDs and
+byte offsets. Each changed object was selected from the Pre13 variable-level
+whitelist.
+
+The aliases remain unsigned 64-bit types. No expression, cast, format string,
+error path, field order, or control flow changed. File sizes, lengths, chunk
+and extent indexes/counts, directory cookies, media sizes, timestamps, disk
+fields, and overflow-only temporaries retain their previous types.
+
+Declarations and definitions were updated together. The resulting source diff
+contains only type tokens, line wrapping required by those tokens, and this
+record.
+
+No build, QEMU, smoke, or feature test was run for this batch.