Index search and double-byte character set

The index search function can be used with either double-byte character set (DBCS) or single-byte character set (SBCS) data. When DBCS data is used, the device from which it is requested must be capable of entering and presenting the data in DBCS.

The object that contains the index search data is marked as containing DBCS data. The system determines if the device is capable of handling the DBCS data.

When the data is being prepared for DBCS format and the index search function is used with that data, consider the following information:

• When the index search data is prepared for a DBCS system, the synonyms entered on the ISCHSYN tag must be in double-byte character mode. That is, the first byte after the tag must be a shift-out character and the last byte of the data must be a shift-in character. The system does not convert data on the ISCHSYN tag to double-byte character data.
• Words must be separated by a single-byte blank. From 1 to 19 double-byte characters can be combined to form a word. Intervening shift-out and shift-in characters are allowed, but are ignored by index search.
• The words that are used to link the ISCH and ISCHSYN tags (the ROOTS attribute of the ISCH tag and the ROOT attribute of ISCHSYN tag) must be identical and should not be entered in DBCS.
• Search words can be entered in either single-byte mode or double-byte mode. Single-byte blanks can be entered to separate the words.

When the search words are shown on the screen, the double-byte character representation (the character that was actually used in the search) is shown. Special processing takes place so that index search is not case sensitive. The search words from the ISCHSYN tag are converted to uppercase using a conversion table for the code page that is specified with the TXTCHRID attribute of the PNLGRP tag. If the search words are DBCS, they are not converted to uppercase. Shift-out and shift-in characters are treated as blanks during parsing; leading and trailing blanks are removed. All SBCS words are converted to uppercase using a conversion table for the code page of the device description.