Invert mark

A ringed note marking an upside-down type.

Also known as: Turned letter mark, Upside down character mark

Engineering & technicalEveryday & digitalStandard profile

Meanings

The proof correction mark identifying a character set upside down.

Officially standardisedVerified fact
Identifies a character set upside down and instructs that it be turned.
Contexts: Technical drawing
Officially standardisedVerified fact
Belongs with the wrong fount mark to a group of faults that only metal type could produce, since digital setting cannot invert one character by accident.
Contexts: Technical drawing

Visual description

A stroke through the inverted character answered by a ringed marginal note giving the instruction.

Symmetry: none
Orientation: upright

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

BS 5261 — Copy preparation and proof correction
British Standards Institution · retrieved 2026-08-21
The British Standard defining proof-correction marks and their marginal counterparts. Paywalled, so records describe the marks as documented in secondary summaries of the standard rather than quoting its text. Authoritative for British practice; American convention differs in several marks.

Last reviewed 2026-08-24

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Meanings

The proof correction mark identifying a character set upside down.

Officially standardisedVerified fact

Identifies a character set upside down and instructs that it be turned.

Contexts: Technical drawing

Officially standardisedVerified fact

Belongs with the wrong fount mark to a group of faults that only metal type could produce, since digital setting cannot invert one character by accident.

Contexts: Technical drawing

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

BS 5261 — Copy preparation and proof correction
British Standards Institution · retrieved 2026-08-21
The British Standard defining proof-correction marks and their marginal counterparts. Paywalled, so records describe the marks as documented in secondary summaries of the standard rather than quoting its text. Authoritative for British practice; American convention differs in several marks.

Last reviewed 2026-08-24