Leading-= policy for a 'formula' field (a 'reference' field never takes one — a typed = is
an invalid character there, part of its "limit input" contract).
Two facets in one policy — what the user may TYPE, and how a committed value DISPLAYS (see
formulaDisplayText):
'optional' (default) — =SUM(A1) and SUM(A1) mean the same formula; the text stays as typed
while typing. A committed value displays =-prefixed.
'required' — text without a leading = reads as an error. For fields where the = is part of
the contract (a name's refers-to) rather than a convenience. Displays =-prefixed.
'bare' — the field READS bare: a committed value displays WITHOUT the = (a typed one is still
accepted, and the next re-derive drops it). For fields whose stored expression carries no = on
the wire — a conditional format's scale stop or expression param.
'literal' — the = DECIDES: text with a leading = is a formula (parsed, colored, validated),
text without one is a literal that is never parsed and never an error — Excel's own cellIs/DV
operand box. A committed string value displays verbatim; the = is the one discriminator, so
the field adds none and strips none.
Leading-
=policy for a'formula'field (a'reference'field never takes one — a typed=is an invalid character there, part of its "limit input" contract).Two facets in one policy — what the user may TYPE, and how a committed value DISPLAYS (see
formulaDisplayText):'optional'(default) —=SUM(A1)andSUM(A1)mean the same formula; the text stays as typed while typing. A committed value displays=-prefixed.'required'— text without a leading=reads as an error. For fields where the=is part of the contract (a name's refers-to) rather than a convenience. Displays=-prefixed.'bare'— the field READS bare: a committed value displays WITHOUT the=(a typed one is still accepted, and the next re-derive drops it). For fields whose stored expression carries no=on the wire — a conditional format's scale stop orexpressionparam.'literal'— the=DECIDES: text with a leading=is a formula (parsed, colored, validated), text without one is a literal that is never parsed and never an error — Excel's own cellIs/DV operand box. A committed string value displays verbatim; the=is the one discriminator, so the field adds none and strips none.