MACF Chunk

See more on Chunks in general.

This is a Macintosh Finder Info record.

MACF Chunk structure


The a (correlated) Flag must be set.

The b (subtype) Flag must be set.

The r (range of instances) , p (multi-part) & c, and y (payload specification) flags are all available. The i (instance sizes field is present) flag must be cleared.

The y flag may be present. A MACF-r containing lots of identical instances may compress very well.

MACF-nd has a distinct meaning, documented below.


Subtype is set to 66 (hex 42).

Instance Number

The Instance Number matches the Instance Number of the DATA it applies to, as with any a-flagged chunk type.

MACF Chunk Payload

The Payload contains the 16-byte Macintosh Finder Info record that is native on the Macintosh.

∴Should give structure details and information about the Mac.

Usage Notes

If extracted on other platforms, this information can be used to add file extensions or otherwise indicate the file’s “type” on the target system.


MACF-nd Chunk

A portion number, as with DATA.

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