Screen Attributes

Attribute bytes

• The location and look of screen fields are controlled by special characters called attribute bytes.
• An attribute byte takes up one screen position but is displayed as a blank.
• A field starts immediately after its attribute byte and ends immediately before the next field's attribute byte.
• A data entry field needs two attribute bytes: one to mark its beginning and one to mark its end.

Standard attributes

• Protection: UNPROT lets the user type; PROT is display-only; ASKIP (skip) is protected and the cursor jumps automatically to the next unprotected field.
• Shift: alphanumeric is the default (left-justified, space-filled); numeric (NUM) turns on the numeric lock - the field is right-justified and zero-filled.
• Intensity: normal (NORM), bright (BRT), or dark (DRK) - a dark field shows only blanks no matter what it contains.
• Bit positions in the attribute byte: bits 2-3 set protection and shift, bits 4-5 set intensity, bit 6 must be 0, bit 7 is the MDT.
• Common bit settings: 00 = unprotected alphanumeric, 01 = unprotected numeric, 10 = protected, 11 = protected skip; intensity 10 = bright, 11 = dark.

Extended attributes

• Extended color: BLUE, RED, PINK, GREEN, TURQUOISE, YELLOW or NEUTRAL.
• Extended highlighting: blinking (field flashes), reverse video (dark characters on light background), underline.
• Validation: must-enter (user must type at least one character), must-fill (every position must be filled), trigger (field is transmitted as soon as the cursor leaves it).
• Programmed symbols: up to 6 alternate user-definable character sets.