This short doc presents the filter file format for the perl web front-end :

the name of the filter is the name of the file, minus its extension (.flt)
so slashes '/' are forbidden (to avoid wild directory browsing)

here is a sample flt file :

comment=test with multicriteria filter : address S 81.96.66 && Class.name C ICMP
desc=1
by_page=30
Formula=A AND B
A=Address|address|S|81.91.66
B=Classification|name|C|ICMP

as you see, there are several field types : (no specific order)
  - comment (mandatory) : one line comment about what this filter does

  - desc (mandatory) : if 1, reverse display order (Last -> First). other = 0
  - by_page (mandatory) : number of results per page

  - Formula (mandatory) : contains boolean operations between criterias
      allowed elements : AND/OR/NOT, brakets, criteria names (A -> Z)

  - Criteria (1 at least) :
      letter (A-Z in uppercase) : identify the criteria in the formula
      value : (fields separated by a pipe (|)
        Table name : case sensitive
        Field name : case sensitive (even if all fields are lower-case)
        Operator : (case sensitive)
          =  : equals to
          != : differs from
          >  : is greater than
          <  : is lower than
          >= : is greater or equal
          <= : is lower or equal
          S  : starts with
          C  : contains
          E  : ends with
          M  : matches (% as wild-card)
        Value : case insensitive
