Enscribe Programmer's Guide

NOTE: For entry-sequenced and relative files, generic positioning by the primary key is the
equivalent of exact positioning.
Exact Positioning
Exact positioning means the only records accessed are those whose key field, as designated by
the current key specifier, contains a value that is both:
• exactly as long as the specified comparison length
• equal to the current key value.
When the current key no longer matches, an EOF indication is returned. Exact positioning accesses
no more than one record.
Alternate Keys
For each file having one or more alternate keys, at least one alternate-key file exists. Each record
in an alternate-key file consists of:
• Two bytes for the key-specifier
• The alternate-key value
• The primary-key value of the associated record in the primary file
Thus, the length of an alternate-key record in bytes, is:
2 + alternate-key field length + primary-key length
Figure 9 (page 32) shows how alternate keys are implemented.
Alternate Keys 31