TABPACK()
 Converts spaces in tabs
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 Syntax

     TABPACK(<cString>,[<nTabWidth>],
        [<cCharacter|nCharacter>]) --> cString

 Arguments

     <cString>  Designates a character string that is packed with tab
     characters.

     <nTabWidth>  Designates the tab width.  The default value is 8.

     <cCharacter|nCharacter>  Designates which characters are replaced by
     a tab.  The default value is a space, CHR(32).

 Returns

     TABPACK() returns the modified character string.

 Description

     This function does not simply exchange a simple sequence of the same
     characters for a tab; instead, it takes into account the true tab
     positions.  If a space (or the <cCharacter|nCharacter>) is found at a
     tab position, and immediately preceding it there is at least one
     identical character, the function replaces this sequence (maximum
     <nTabWidth>) with a CHR(9).  With tab characters, text can be packed by
     individual tab widths.  As with every good text editor, there is no
     replacement with a tab within single or double leading characters.

 Notes

     .  For the beginning of a line, the function takes into account
        the "normal" carriage return (CHR(13)/CHR(10)) as well as the high
        bit return (CHR(141)) used by MEMOEDIT().  Previously existing tab
        characters are also taken into account.

     .  If another tab already exists, this tab can be removed with
        TABEXPAND().  The new tab can then be inserted using TABPACK().

 Example

     We have avoided replacing spaces with tabs in the following examples to
     keep the example legible.  Tab width is 8 (default).  "*" is exchanged
     for tab characters.

     ? TABPACK("AAAAAAA*", "*")           // "AAAAAAA*"
     ? TABPACK("AAAAA***", "*")           // "AAAAA" + CHR(9)

     ? TABPACK("AAAAA*****", "*")         // "AAAAA" + CHR(9) + "**"
     crlf   :=  CHR(13) + CHR(10)
     cText  :=  "ABCD+" + crlf + "++---+++++"
     ? TABPACK(cText, 4, "+")             // "ABCD+" + crlf +
                                          // "++---" + CHR(9) + "++"