OpenType 1.8 Errata

This page documents errors in the OpenType specification that have technical significance and could lead to incorrect implementations. The scope is limited to issues in which the OpenType 1.8 specification as originally published implies technical details that are contrary to the intended design. Corrections may include corrections to incorrect values related to certain table fields, incorrect formulas for computing certain values, or similar issues. Corrections will not include any changes to data structures. If the textual change required for the correction is minor, the correction will be made in the specification and also listed here. If larger textual changes are required, the issue may be described here, but actual changes may be left to a future version. In either case, the status will be indicated in the table below.

Certain minor, editorial errors such as mis-spelling of words with no technical impact may on occasion be corrected silently, without notice or version update.

Date	Page	Description	Status
17 August 2020	The TrueType Instruction Set	When content was ported from Microsoft Word, some incorrect text was inadvertently added to the description of Round to Half Grid (RTHG).	Corrected in 1.8 (archived) (2020-8-17)
17 August 2020	The TrueType Instruction Set	When content was ported from Microsoft Word, an error was inadvertently introduced to the description of logical OR.	Corrected in 1.8 (archived) (2020-8-17)
17 August 2020	The TrueType Instruction Set	When content was ported from Microsoft Word, the MIRP Code range was incorrectly described as 0xC0 - 0xDF. The correct range is 0xE0 - 0xFF.	Corrected in 1.8 (archived) (2020-8-17)
12 January 2017	avar — Axis Variations Table	The table describing the 'avar' header was missing a field that is required for compatibility with Apple’s specification of 'avar' table. A reserved USHORT field should exist after the minorVersion field and before the axisCount field.	Corrected in 1.8 (2017-1-12)
14 December 2016	CFF 2 CharString Format	In Table 1, CFF 2 Charstring Encoding Values, the byte value ranges in rows 9 and 10 both specify “247 — 250”. This is correct for row 9, but incorrect for row 10. The correct value range for row 10 is “251 — 254”.	Will be corrected in the next version.
11 November 2016	OS/2 — OS/2 and Windows Metrics	In the table defining bits for ulUnicode1 – ulUnicodeRange4, the entry for bit 90 gave the block range for Private use (plane 15) as “FF000-FFFFD”. The block range should be “F0000-FFFFD”.	Corrected in 1.8 (2016-11-11)
17 October 2016	HVAR — Horizontal Metrics Variations Table	In the paragraphs following the table that describes the DeltaSetIndexMap format, the entryFormat field was referred to twice as “the width field”; these should say “the entryFormat field”.	Corrected in 1.8 (2016-10-17)
17 October 2016	HVAR — Horizontal Metrics Variations Table	The formulas for computing outerIndex and innerIndex were missing expressions to reflect that the innerIndexBitCountMask bits represent a count minus one. In both formulas, “(entryFormat & innerIndexBitCountMask)” should be “((entryFormat & innerIndexBitCountMask) + 1)”.	Corrected in 1.8 (2016-10-17)
17 October 2016	STAT — Style Attributes Table	In the table describing the AxisValueFormat3 format, the description for the Format field said “set to 1” but should say “set to 3”.	Corrected in 1.8 (2016-10-17)