Thus, such automata usually function correctly with most of the data but they have a less clear relation with original intended rules. The rule compiler described below rectifies this problem by letting the linguist write rules in a true rule formalism while the computer produces the automata mechanically. These can then be used in conventional two-level programs, both for testing and and for production use. Several two-level descriptions are now on their way towards completion using the compiler. Furthermore, the equal sign is no longer used for denoting the full lexical or surface alphabet.
V stands for two successive surface vowels.
Another difference is in the formalism for collapsing several similar rules into one rule. Note that surface and lexical alphabets are declared separately. This guarantees that the role of each segment is uniquely determined. The sets are separate also because it is not always evident e.g. which segments are considered to be vowels on the lexical level. Another effect of the expansion of ''where'' clauses is the introduction of some new character pairs.