Usage Codes for Extra Header and Extra Entry Fields

The following are valid usage codes for elements in the aulExHdrFldUsage and aulExEntFldUsage arrays, both of which are fields of the CTOC header. These arrays define the meaning of data stored in the aulExHdrField and aulExEntField "extra fields." All usage codes apply to both header fields and entry fields, unless explicitly stated otherwise.

Values marked in the extra header field arrays generally apply to all elements in the CFRG chunk, while values marked in the extra entry field arrays generally apply only to the element referenced by the corresponding CTOC table entry.

CTOC_EFU_UNUSED (0x00)

The field is unused. This usage code may be used to logically delete a header field.
CTOC_EFU_LASTMODTIME (0x01)
When used to describe an extra header field, the field contains the time that any portion of the CTOC or CGRP was last modified.

When used to describe an extra entry field, the field contains the time that the corresponding CTOC table entry, or the compound file element it refers to, was last modified.

The field is interpreted as a ULONG containing the number of seconds that have elapsed since 00:00:00 Greenwich Mean Time (GMT), January 1, 1970.

CTOC_EFU_CODEPAGE
The field contains the code page and country code for the achName field. These values override any values specified in a CSET chunk.

When used to describe an extra header field, the field contains code-page and country-code information for all CTOC table entries. When used to describe an extra entry field, the field contains information for that specific CTOC table entry.

The low-order word of the field contains one of the following code page values:

Zero

Use standard ISO 8859/1 code page. This is identical to code page 1004 without code points defined in hex columns 0, 1, 8, and 9.

CTOC_CHARSET_CODEPAGE (0x0000nnnn)

Use code page 0xnnnn, where 0xnnnn is the 16-bit code page number. For example, 0x00000352 for OS/2 code page 850, or 0x000004E4 for Windows 3.1 code page 1252.

The high-order word contains one of the following country codes:

Zero

Ignore this field.

Country code

See Country Codes for a list of currently defined country codes.

CTOC_EFU_LANGUAGE
The field contains language and dialect information for the achName field. These values override any values specified in a CSET chunk.

When used to describe an extra header field, the field contains language information for all CTOC table entries. When used to describe an extra entry field, the field contains information for that specific CTOC table entry.

The low-order word of the field contains one of the following language codes:

Zero

Ignore this field.

Language code

See Language and Dialect Codes for a list of currently defined language codes.

The high-order word of the field contains one of the following dialect codes:

Zero

Ignore this field.

Dialect code

Select Language and Dialect Codes for a list of currently defined dialect codes.

CTOC_EFU_COMPRESSPARAM0 (0x05) through CTOC_EFU_COMPRESSPARAM9 (0x14)
Specifies a compression parameter. See Compression of Compound File Elements.

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