PidTagAttachTag Canonical Property

Applies to: Outlook 2013 | Outlook 2016

Contains an ASN.1 object identifier specifying the application that supplied an attachment.

Associated properties:
Data type:
Message attachment


This property identifies the application that originally generated the attachment.

Note The PR_ATTACH_ENCODING (PidTagAttachEncoding) and PR_ATTACH_TAG properties should not be confused. They are not paired or related. PR_ATTACH_ENCODING identifies the algorithm used to transform the data in an attachment. "Object" has a much more general meaning in the term object identifier, and in X.400 usage, than in object-oriented programming.

The object identifier syntax and sample object identifiers are defined in the MAPIOID.H header file. Values for PR_ATTACH_TAG are not limited to those defined in MAPIOID.H.

For complete information on these object identifiers, see the documentation on ASN.1, X.208, and X.209. The object identifier is found in the application-reference element of the File Transfer Body Part (FTBP) environment.

Protocol specifications


Handles message and attachment objects.

Header files


Provides data type definitions.


Contains definitions of properties listed as alternate names.

See also

PidTagAttachMimeTag Canonical Property

MAPI Properties

MAPI Canonical Properties

Mapping Canonical Property Names to MAPI Names

Mapping MAPI Names to Canonical Property Names