The unit of operation is a set of lines ("associative range") and individual lines are identified with a line number in the range 0.0 to 99999.999; leading zeros in the integer part and trailing zeros in the fractional part may be omitted. The user can specify a line number in any of the following ways  Wylbur libraries have a nonstandard format, however it allows the user to export to native OS files with integer sequence numbers and to import native OS files with integer sequence and rescale the line number by a factor of 1000. A range can be specified as a combination of  A pattern is similar to a regular expression, but the syntax is closer to that of SNOBOL than to that of Unix or Perl, there is no backtracking and only the NIH Wylbur has capture of subpatterns. A pattern may be:  Sample commands CHANGE 73/80 TO X10+10 IN EVERY 3RD LINE OF 'ABC' 1/3 in 1.5-2/3.7+2 COPY 'BAL' 10/15 TO EMD CHANGE 73/80 TO " IN EVERY 3RD LINE START 2 OF 'BAL' 10/15 CHANGE '(' DIGITS*3 ')' TO SUBSTRING 2/4 The specification of base+increment means that the replacement text on the first line is base and is incremented on subsequent lines, so that "X10+10" replaces the matched text on the first line with "X10", on the second line with "X20" and on the third line with "X30". The specification of SUBSTRING 2/4 means columns 2-4 of the matched string; note that this is less flexible than captures. Various organizations developed enhanced versions of Wylbur. These included  SuperWylbur has several enhancements over the original Wylbur. The most important are  The macro processor adds commands, constants, functions and expressions to Wylbur. Even when the command syntax does not include parameters defined to be expressions, the user can use the forms %(expression) and %%(expression) to force evaluation. If the expression is a function with no argument or a variable then the parentheses may be omitted, e.g., %.TIME instead of %(.TIME). A doubled % requests that the valued be quoted. SuperWylbur has two types of constants:  SuperWylbur operators whose names contain only special characters need not be separated by spaces.