Changes between 2.1 beta-test release of June '89 and previous release:

    User-visible:

	- -p flag generates a performance report to stderr.  The report
	  consists of comments regarding features of the scanner rules
	  which result in slower scanners.

	- -b flag generates backtracking information to lex.backtrack.
	  This is a list of scanner states which require backtracking
	  and the characters on which they do so.  By adding rules
	  one can remove backtracking states.  If all backtracking states
	  are eliminated, the generated scanner will run faster.
	  Backtracking is not yet documented in the manual entry.

	- Variable trailing context now works, i.e., one can have
	  rules like "(foo)*/[ \t]*bletch".  Some trailing context
	  patterns still cannot be properly matched and generate
	  error messages.  These are patterns where the ending of the
	  first part of the rule matches the beginning of the second
	  part, such as "zx*/xy*", where the 'x*' matches the 'x' at
	  the beginning of the trailing context.  Lex won't get these
	  patterns right either.

	- Faster scanners.

	- End-of-file rules.  The special rule "<<EOF>>" indicates
	  actions which are to be taken when an end-of-file is
	  encountered and yywrap() returns non-zero (i.e., indicates
	  no further files to process).  See manual entry for example.

	- The -r (reject used) flag is gone.  flex now scans the input
	  for occurrences of the string "REJECT" to determine if the
	  action is needed.  It tries to be intelligent about this but
	  can be fooled.  One can force the presence or absence of
	  REJECT by adding a line in the first section of the form
	  "%used REJECT" or "%unused REJECT".

	- yymore() has been implemented.  Similarly to REJECT, flex
	  detects the use of yymore(), which can be overridden using
	  "%used" or "%unused".

	- Patterns like "x{0,3}" now work (i.e., with lower-limit == 0).

	- Removed '\^x' for ctrl-x misfeature.

	- Added '\a' and '\v' escape sequences.

	- \<digits> now works for octal escape sequences; previously
	  \0<digits> was required.

	- Better error reporting; line numbers are associated with rules.

	- yyleng is a macro; it cannot be accessed outside of the
	  scanner source file.

	- yytext and yyleng should not be modified within a flex action.

	- Generated scanners #define the name FLEX_SCANNER.

	- Rules are internally separated by YY_BREAK in lex.yy.c rather
	  than break, to allow redefinition.

	- The macro YY_USER_ACTION can be redefined to provide an action
	  which is always executed prior to the matched rule's action.
	
	- yyrestart() is a new action which can be used to restart
	  the scanner after it has seen an end-of-file (a "real" one,
	  that is, one for which yywrap() returned non-zero).  It takes
	  a FILE* argument indicating a new file to scan and sets
	  things up so that a subsequent call to yylex() will start
	  scanning that file.

	- Internal scanner names all preceded by "yy_"

	- lex.yy.c is deleted if errors are encountered during processing.

	- Comments may be put in the first section of the input by preceding
	  them with '#'.



    Other changes:

	- Some portability-related bugs fixed, in particular for machines
	  with unsigned characters or sizeof( int* ) != sizeof( int ).
	  Also, tweaks for VMS and Microsoft C (MS-DOS), and identifiers all
	  trimmed to be 31 or fewer characters.  Shortened file names
	  for dinosaur OS's.  Checks for allocating > 64K memory
	  on 16 bit'ers.  Amiga tweaks.  Compiles using gcc on a Sun-3.

	- Compressed and fast scanner skeletons merged.

	- Skeleton header files done away with.

	- Generated scanner uses prototypes and "const" for __STDC__.

	- -DSV flag is now -DSYS_V for System V compilation.

	- Removed all references to FTL language.

	- Software now covered by BSD Copyright.

	- flex will replace lex in subsequent BSD releases.
