How Z Data Tools handles segmented data with related ID criteria

Identification criteria
Identification criteria includes the ability to specify one or more references to fields within other segment types that occur earlier in the physical record in relation to the current segment.

Segment types are checked backwards from the current segment location, so the first matching segment type (for the particular related ID reference) preceding the current segment is the one used for comparison. ID criteria and related ID criteria are ANDed together unless ORing is requested by means of the template option.

Selection criteria
Segment selection criteria affects the selection of the entire record. If a segment within a record fails the selection criteria, the entire record is considered to have failed selection and is not presented or available in any form during subsequent processing.
Template layout selection and deselection
Deselection of a segment type in the template does not affect the processing of the selection criteria. For Edit or View, segments that have been deselected in the template (in order to honor the setting) are always grouped in a not-selected shadow line, regardless of the current grouping setting (the SHOW settings). The shadow line may be hidden or visible, depending on the current settings of the SHADOW primary command.
Unidentified segments
Segments that cannot be identified by explicit ID criteria, or by the implicit criteria of length matching (for those segments that do not have ID criteria specified), are also marked as not-selected segments. However, in Edit or View, these continue to obey the current grouping settings. When in Edit or View and in a multi-line format (TABL, CHAR, HEX or LHEX), and these segments are ungrouped, then the prefix area contains "=ID" to denote that these segments could not be identified. In SNGL format (as there is no prefix area), a message is issued.
Identification and selection currency for Edit and View
Identification and selection criteria are only applied to the records and segments at the time of loading the data into memory (assuming selection criteria have been supplied and this is an in-memory Edit or View) for the editor session. They are not re-assessed at any time during the editor session. For Edit, this means that data changes to segments that potentially affect the segment type, or would have disqualified the record or segment for selection, are not acted on in the current Edit session. To reflect this type of change to the data, it may be saved and the edit session re-entered.