Using VPLUS: An Introduction to Forms Design (32209-90004)

3-7
the field tag entered during form layout can be any combination of upper
or lower case letters, such as ordnum. The uppercase name, ORDNUM, is
the name by which the field is identified on the Field Menu, as shown in
Figure 3-6. If you want, you can change the field name to another all
uppercase field name. You may want to do so for several reasons. For
instance, since lowercase letters are never used in the field name, but
only appear in the field tags, the shift to uppercase may force you to
assign a new name to a field so that the field names are unique. Thus,
if you layout a form with two fields tagged respectively, F1 and f1, the
field names displayed on the Field Menus are no longer unique; they both
appear as F1. You must make them unique, using new field names of up to
15 characters long for one or both of the fields. You might also change
a field name to make it more meaningful. For example, suppose the name
TR identifies a two-character field. Changing it to TAX_RATE makes its
function easier to remember.
Topic: Field Menu Fields
The next step in designing this form is to specify the field edits to be
used for each field of this form Figure 3-6.
But before doing this, read the following brief description of the field
attributes issued on all Field Menus.
The Field Number Field
A field number is assigned by FORMSPEC to every field. This number is
initially based on the position of the field on the form (for example,
ordate is field number 1), and this number never changes. If you change
the form layout at a later time so that ordate is no longer the first
field, it is still identified as field number 1. (Note that these field
numbers are not significant unless you use the VPLUS/V intrinsics to
write your own application or to modify ENTRY.)
The Field Length Field
Field length, like the field number, is based on the form layout. The
number of characters you leave between the field delimiters is shown on
the Field Menu as the length of that field. Unlike the field number, the
length changes whenever you change the field size on the form layout. In
our example, 18 character positions were allowed for the date, so ordate
has a field length of 18.
The Field Name Field
Field tags are used when laying out the form--field names are used on the
Field Menu to uniquely identify the field. When the Field Menu is
initially displayed, the field tag is used as the field name by default
and is always shown in uppercase letters. This is because FORMSPEC
automatically shifts any lowercase letters in the field tag (the name
between field delimiters on the form) to uppercase. It does not change