ADR 0274: variation selectors, blank letters and every heading form refused

02-DECISIONS/0274-an-agent-proposes-a-shared-instruction-section-and-every-node-takes-it-only-on-the-operators-warrant-which-it-proves-itself.md

@@ -201,9 +201,10 @@ is what renders. A section set at the terminal is changed there, and a proposal
   text's start or after anything but a letter or a digit** (any whitespace, Unicode's included, or punctuation),
   which the instruction file may read in as a file. Wider than the vendor's pattern on purpose;
 - **what a reader cannot see and a session reads**: a control character but a line break and a tab, a format
-  character (zero-width characters, bidirectional overrides, the tag block), private use, a noncharacter, and any
-  space or separator but the plain space. The operator approves what was shown, so nothing unshown may ride along;
-- a heading of level one to three, which would read as one of the managed file's own sections;
+  character (zero-width characters, bidirectional overrides, the tag block), a variation selector, a letter that
+  shows blank, private use, a noncharacter, and any space or separator but the plain space. The operator approves what was shown, so nothing unshown may ride along;
+- a heading of level one to three, in any of its forms (`#`, a line underlined with `=` or `-`, HTML), which would
+  read as one of the managed file's own sections;
 - anything shaped like a secret (a key block, a known token's shape, a value given to a secret's name), because the
   text is read by every session and shown on a phone;
 - an empty text, one that is not text, or **more than 16 KiB**: every session reads all of it, every time;