The Master File describes the
following field characteristics:
- The name of
the field, as identified in the FIELDNAME attribute.
- Another name
for the field, either its original name, as defined to its native
data management system, or (for some types of data sources) a synonym
of your own choosing, or (in some special cases) a pre-defined value
that tells how to interpret the field, that you can use as an alternative
name in requests. This alternative name is defined by the ALIAS
attribute.
- How the field
stores and displays data, specified by the ACTUAL, USAGE, and MISSING
attributes.
The ACTUAL attribute describes the type and length
of the data as it is actually stored in the data source. For example,
a field might be alphanumeric and 15 characters in length. Note
that FOCUS data sources do not use the ACTUAL attribute, and instead use
the USAGE attribute to describe the data as it is formatted. WebFOCUS handles
the storage.
The USAGE attribute, also known by its alias,
FORMAT, describes how a field is formatted when it appears in reports.
You can also specify edit options, such as date formats, floating
dollar signs, and zero suppression.
The MISSING attribute
enables null values to be entered into and read from a field in
data sources that support null data, such as FOCUS data sources
and most relational data sources.
- The option for
a field to be virtual, rather than being stored in the data source,
and have its value derived from information already in the data
source. Virtual fields are specified by the DEFINE attribute.
- Optional field
documentation for the developer, contained in the DESCRIPTION attribute.
- Acceptable data-entry
values for the field, specified by the ACCEPT attribute.
- An alternative
report column title for the field, described by the TITLE attribute.
- A 100-year window
that assigns a century value to a two-digit year stored in the field.
Two attributes define this window: DEFCENT and YRTHRESH.