Dynamic modification of EGCS data

EGCS data can also be dynamically modified to permit EBCDIC or EGCS data to be mapped to a particular field on the 3270 display.

With this function:

  • You can enter EBCDIC or EGCS data.
  • The application program can receive EBCDIC or EGCS data.
  • EBCDIC or EGCS data can be passed to an SLU P remote program or to an ISC subsystem.

If ATTR=(,nn) is specified in the MFLD statement and a programmed symbol attribute is specified in the corresponding DFLD statement, the application program can modify the field programmed symbol attribute. Dynamic modification of the programmed symbol attribute for EGCS requires two additional bytes. These additional bytes precede the MFLD data and must be included in the MFLD LTH= specification.

The IMS application program can modify the DFLD programmed symbol attribute if all the following conditions are met:

  • The DFLD specifies EATTR=PX'hh', PC'c', EGCS'hh' or EGCS.
  • The corresponding MFLD statement specifies ATTR=(,nn), where nn is a value from 1 through 4.
  • The application program includes 2 × nn additional bytes preceding the data field.
  • One set of two attribute bytes has an X'C3' as its first byte and a valid value (X'00' or X'40'—X'FE') as its second byte.

The following table illustrates what the MFS transmits in the value byte of the programmed symbol attribute type, if the DFLD statement does or does not specify a programmed symbol attribute, and the IMS application program does or does not modify it.

Table 1. Attribute type value byte contents
Application Program Programmed Symbol Attribute Bytes of X and: C3 EATTR= ATTR= EATTR=
  Programmed symbol specified Programmed symbol default Not specified
X'40_FE'1 Send X'40_FE' Send X'40_FE' Send no attribute
Default X'00'1 Send X'00' Send X'00' Send no attribute
Not specified 2 Send programmed symbol DFLD specification Send no attribute N/A
Omitted or Invalid 3 Send programmed symbol DFLD specification Send X'00' Send no attribute
Notes:
  1. ATTR=nn is specified on at least one MFLD statement that maps to this DFLD statement. The IMS application program specifies a programmed symbol attribute of X'40' to X'FE'.
  2. ATTR=nn is not specified on any MFLD statement that maps to this DFLD statement.
  3. ATTR=nn is specified on at least one MFLD statement that maps to this DFLD statement. The application program omits specifying this attribute, or the specified attribute is not X'00' or X'40' to X'FE'.