function _size75( $string ) {
    $strlen = strlen( $string );
    $tmp    = $string;
    $string = null;
    while( $strlen > 75 ) {
       $breakAtChar = 75;
       if( substr( $tmp, ( $breakAtChar - 1 ), strlen( '\n' )) == '\n' )
         $breakAtChar = $breakAtChar - 1;
       $string .= substr( $tmp, 0, $breakAtChar );
       $string .= $this->nl;
       $tmp     = ' '.substr( $tmp, $breakAtChar );
       $strlen  = strlen( $tmp );
    } // while
    $string .= rtrim( $tmp ); // the rest
    if( $this->nl != substr( $string, ( 0 - strlen( $this->nl ))))
      $string .= $this->nl;
    return $string;
  }
function _size75( $string ) {
    $strlen = strlen( $string );
    $tmp    = $string;
    $string = null;
    while( $strlen > 75 ) {
       $breakAtChar = 75;
       if( substr( $tmp, ( $breakAtChar - 1 ), strlen( '\n' )) == '\n' )
         $breakAtChar = $breakAtChar - 1;
       $string .= substr( $tmp, 0, $breakAtChar );
       $string .= $this->nl;
       $tmp     = ' '.substr( $tmp, $breakAtChar );
       $strlen  = strlen( $tmp );
    } // while
    $string .= rtrim( $tmp ); // the rest
    if( $this->nl != substr( $string, ( 0 - strlen( $this->nl ))))
      $string .= $this->nl;
    return $string;
  }
function _size75 ( $ string ) { $ strlen = strlen ( $ string ) ; $ tmp = $ string ; $ string = null ; while ( $ strlen > 75 ) { $ breakAtChar = 75 ; if ( substr ( $ tmp , ( $ breakAtChar - 1 ) , strlen ( '\n' ) ) == '\n' ) $ breakAtChar = $ breakAtChar - 1 ; $ string .= substr ( $ tmp , 0 , $ breakAtChar ) ; $ string .= $ this -> nl ; $ tmp = ' ' . substr ( $ tmp , $ breakAtChar ) ; $ strlen = strlen ( $ tmp ) ; } // while $ string .= rtrim ( $ tmp ) ; // the rest if ( $ this -> nl != substr ( $ string , ( 0 - strlen ( $ this -> nl ) ) ) ) $ string .= $ this -> nl ; return $ string ; }
break lines at pos 75

Lines of text SHOULD NOT be longer than 75 octets, excluding the line
break. Long content lines SHOULD be split into a multiple line
representations using a line "folding" technique. That is, a long
line can be split between any two characters by inserting a CRLF
immediately followed by a single linear white space character (i.e.,
SPACE, US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
of CRLF followed immediately by a single linear white space character
is ignored (i.e., removed) when processing the content type.

Edited 2007-08-26 by Anders Litzell, anders@litzell.se to fix bug where
the reserved expression "\n" in the arg $string could be broken up by the
folding of lines, causing ambiguity in the return string.
Fix uses var $breakAtChar=75 and breaks the line at $breakAtChar-1 if need be.

@author Kjell-Inge Gustafsson <ical@kigkonsult.se>
@since 2.2.8 - 2006-09-03
@param string $value
@return string
break lines at pos 75