Working with Tags

The tag of a data element consists of an ordered pair of 16-bit values that represent a Group number and an Element number. The tag indicates the type of information stored in the value field of the data element. There are a number of tags that are standard for the DICOM file format. In addition to the standard tags, user-defined tags may also be added.

LEADTOOLS maintains a table (or list) internally of all available tags, standard and user defined. In this documentation the table of available value representations will be referred to as the Data Element Tag Table. Also provided in this documentation is a table of the default values for the standard tags. To see these default values, refer to the Default Data Element Tag Table.

LEADTOOLS provides a number of functions for maneuvering through and modifying the Data Element Tag Table. All functions pertaining to the Data Element Tag Table have the form L_DicomxxxTag.

For maneuvering through the Data Element Tag Table, LEADTOOLS provides the following functions:

L_DicomGetFirstTag

L_DicomGetLastTag

L_DicomGetPrevTag

L_DicomGetNextTag

L_DicomGetCountTag

To find specific items, based on either the tag or an index into the table, use L_DicomFindTag and L_DicomFindIndexTag.

To insert new items in the Data Element Tag Table, call L_DicomInsertTag.

You can delete individual items from the table using L_DicomDeleteTag, or you can delete all items from the table, using L_DicomResetTag.

To change the name of an item already in the table, call L_DicomSetNameTag.

To determine whether you have a valid pointer to an Data Element Tag item, call L_DicomExistsTag.

Finally, to reset the Data Element Tag Table to the default values, use L_DicomDefaultTag.

For more information on tags, refer to An Overview of the DICOM File Format or the DICOM Standard.

For a list of macros available for use, refer to DICOM Macros.