Altering the Sequence

You can specify an alternate sequence in the altseq parameter of the HPSORTINIT or HPMERGEINIT intrinsic. (The default sequence is ASCII.) Only ASCII type is allowed to request alternate sequences; when you specify an alternate collating sequence, you must set the keys parameter data type to zero (byte data).

The altseq parameter accepts a array.

The first element of the array is set by the following table. The rows of the table show the type of data you are sorting, and the columns of the table show the type of sequence you want. For alternate sequences, set the first element of the altseq parameter to CHR(0).

In the second element of the array, specify a number one less than the total number of characters in the collating sequence (n - 1). ASCII has 256 characters, for example, so for ASCII (the default), the second element would be CHR(255).

If the first element is CHR(0), the rest of the elements of the altseq parameter array contain your actual collating sequence. The collating sequence may be explicitly specified or read from a file. The sequence must start in the third element of the altseq array.

You can create a file that contains a collating sequence, using the SORT/XL or MERGE/XL utilities. For example, if you want to create the collating sequence mentioned above (AaBbCc ... ) with the SORT/XL utility, you would do the following:

   :FILE DISPLOUT=ALTSEQ,NEW; SAVE; REC=-80,,F,ASCII; DEV=DISC
   :RUN SORT.PUB.SYS
 
   >DATA IS ASCII, SEQUENCE IS ASCII
   >ALTSEQ MERGE "A-Z" with "a-z"
   >SHOW TABLE, OFFLINE
   >EXIT

Now you have created an ASCII file named ALTSEQ that contains the new collating sequence in a table, a decimal list, and an octal list.

Edit the file to contain only the decimal list of the sequence. From your sorting or merging program, read in the sequence from the file ALTSEQ, and put the character representations of the values into elements 3-258 of the parameter altseq.

For more information about using SORT-MERGE/XL to create alternate collating sequences, refer to SORT-MERGE/XL General User's Guide.