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Fields and Attributes

Identifying Fields

Many SDK methods interact with fields. For example, your application can perform the following tasks:

The Screen object methods identify fields by detecting certain changes in the attributes of each field. The attributes that define fields are unique to each host. For example, a field label might be blinking, but these character attributes do not indicate the beginning of a new field.

The following table lists the attributes of each host and whether they denote a field.

Terminal Type
New Field?
T27 Protected text, Protected field, Unprotected field, Left and Right Justified Yes
Intensity (Normal and Bright), Blinking, Reverse Video, Secured (video off) No
UTS Protected area, Unprotected area, Numeric only data, Alphabetic only data, Left and Right Justified Yes
Color, Emphasis No
VT Normal, Bold, Blink, Reverse Video, Invisible, Underscore, Line attributes (double width, double height) Yes
TopBottom attribute, Foreground color No
Note For T27 host sessions, a field within field delimiters can be protected or unprotected. The protected field, however, is not considered the same as protected text, which exists outside the field delimiters.

For VT host sessions, every field is unprotected. Also, the TopBottom attribute is only valid if the line attributes are set to double width/double height. This attribute indicates which half of the text is being shown. Typically, a new line always denotes a field change, except when the next line is the bottom half of a double-height line.

The ALC emulation is driven by a 7-bit protocol that does not include field attributes.

Auto-Skip Fields

When your application sends keystrokes (using the sendKeys method) to an unprotected field in a formatted presentation space, the cursor automatically skips to the beginning of the next available field after data is entered in the last character space of a field.

The only exception is when the field attribute of the next available field is set for protected mode and numeric data types. Protected numeric fields are called auto-skip fields; the cursor bypasses them for the next unprotected field.

You must consider these fields when using the sendKeys method, since this method inserts keystrokes in the presentation space at the current cursor location.

Related Topics
The Presentation Space
Keystroke Reference