>I use them for numeric fields that form a key. For instance:
>
>

>CREATE CURSOR xl_cellxfs (workbook I, id I, numFmtId I, fontId I, fillId I, borderId I, halign C(8), valign C(8), indent I, wraptext I, rotation I)
>INDEX ON BINTOC(workbook)+BINTOC(id) TAG id FOR !DELETED()
>INDEX ON BINTOC(workbook)+PADL(id, 10, '0') TAG sortorder FOR !DELETED()
>

Those are not binary indexes..