Editing IBM 3270 (section)

====Attributes====
The 3270 has three{{sfn|3270 Data Stream|pp=[http://bitsavers.org/pdf/ibm/3270/GA23-0059-4_3270_Data_Stream_Programmers_Reference_Dec88.pdf#page=27 1-6–1-9]}} kinds of attributes:
* [[#Field attributes|Field attributes]]
* [[#Extended attributes|Extended attributes]]{{efn|name=extended}}
* [[#Character attributes|Character attributes]]{{efn|name=extended}}

=====Field attributes=====
The original 3277 and 3275 displays used an 8-bit field attribute byte{{sfn|3270 Data Stream|loc=[http://bitsavers.org/pdf/ibm/3270/GA23-0059-4_3270_Data_Stream_Programmers_Reference_Dec88.pdf#page=27 Field Attributes]|pp=1-6—1-7}} of which five bits were used.<ref name=CompDesc />{{rp|p.18}}
* Bits 0 and 1 are set so that the attribute will always be a valid EBCDIC (or ASCII) character.
* Bit 2 is zero to indicate that the associated field is ''unprotected'' (operator could enter data) or one for ''protected''.
* Bit 3 is zero to indicate that this field, if unprotected, could accept alphanumeric input. One indicates that only numeric input is accepted, and automatically shifts to numeric for some keyboards.
* Bit 4 and 5 operate in tandem: 
** '00'B indicate that the field is displayed on the screen and is not ''selector-pen detectable''.
** '01'B indicates that the field is displayable and selector-pen detectable.
** '10'B indicates that the field is ''intensified'' (bright), displayable, and selector-pen detectable.
** '11'B indicates that the field is non-display, non-printable, and not pen detectable. This last can be used in conjunction with the modified data tag to imbed static data on the screen that will be read each time data was read from the device.
* Bit 7 is the "Modified Data Tag", where '0' indicates that the associated field has not been modified by the operator and '1' indicates that it has been modified. As noted above, this bit can be set programmatically to cause the field to be treated as modified.

Later models include ''base color'': "Base color (four colors) can be produced on color displays and color printers from current 3270 application programs by use of combinations of the field intensify and field protection attribute bits. For more information on color, refer to IBM 3270 Information System: Color and Programmed Symbols, GA33-3056."{{sfn|3270 Data Stream|loc=[http://bitsavers.org/pdf/ibm/3270/GA23-0059-4_3270_Data_Stream_Programmers_Reference_Dec88.pdf#page=27 Field Attributes]|pp=1-6—1-7}}{{rp|1–7}}

=====Extended attributes=====
The [[IBM 3278|3278]] and [[IBM 3279|3279]] and later models used ''extended attributes''{{sfn|3270 Data Stream|loc=[http://bitsavers.org/pdf/ibm/3270/GA23-0059-4_3270_Data_Stream_Programmers_Reference_Dec88.pdf#page=28 Extended Field Attributes]|p=1-7}} to add support for seven colors, blinking, reverse video, underscoring, field outlining, field validation, and programmed symbols.

=====Character attributes=====
The [[IBM 3278|3278]] and [[IBM 3279|3279]] and later models allowed attributes on individual characters{{sfn|3270 Data Stream|loc=[http://bitsavers.org/pdf/ibm/3270/GA23-0059-4_3270_Data_Stream_Programmers_Reference_Dec88.pdf#page=28 Character Attributes]|pp=1-7—1-9}} in a field to override the corresponding field attributes.

This allowed programs (such as the [[LEXX (text editor)|LEXX]] text editor) to assign any font (including the programmable fonts), colour, etc. to any character on the screen.