OLE fields

The OLE fields should actually rather be called long binary fields. They can contain a number of different kinds of values. I know of the following:

Classic packages, as described elsewhere
Modern packages, found in Access 2007 and later, possibly marked by 0x1000 column flag
Binary LV data in the catalog

Modern packages

They start with an 8 byte header:

Name	Length	Type	Description
Storage Type	4 bytes	`UINT 32 LE`	`0` Uncompressed package `1` Compressed package (DEFLATE)
Uncompressed Size	4 bytes	`UINT 32 LE`	The uncompressed size of the package.

The package then follows this header. If it is a compressed package, the bytes are compressed using the DEFLATE algorithm. Use the zlib library to uncompress them.

The package consists of a short header and the payload:

Name	Length	Type	Description
Package Header Length	4 bytes	`UINT 32 LE`	The total length of this header. The payload size is (uncompressed size) - (package header length)
Unknown	4 bytes	`UINT 32 LE`	Contains the value 1
Extension Length	4 bytes	`UINT 32 LE`	The length (in characters) of the file name extension / file type.
Extension	2n bytes	`CHAR 16 LE`	The file name extension of the payload, zero terminated, in UCS-2 / UTF-16.

The rest of the package is the payload, ie. the wrapped file.