Peter Relson wrote <begin extract> There are quite a few keyword ordering requirements within the grammar of PROGxx. <end extract>
This is not in itself objectionable, or even surprising. It corresponds roughly to a classical distinction between positional parameters, which are ordered, must appear in a prescribed sequence, and keyword parameters, which are not, may appear in any sequence. What is wanting in the documentation is 1) any generic discussion of this distinction and 2) clear identification of which is is which; and eliminating these lacunæ would possible without heroic effort. There are other questions that different people will answer differently. I personally do not think that 'keyword' is used felicitously here. The use of the term 'keyword', as opposed to 'reserved word' ordinarily implies context sensitivity but not an ordering requirement following the first, statement-identifying keyword. The syntax of PL/I non-assignment statements, from which that of command-level CICS, some but not all IBM utilities' control statements, and much else are derived, permits, for example, open file(file) buffered record sequential input ; open input file(file) record sequential buffered ; open buffered record input file(file) sequential ; etc., etc. Here the statement-identifying keyword 'open' must come first, but the option keywords following it, only some of which have associated arguments, may appear in any order. This syntax, which is very easy to parse, has much to recommend it. Regrettably, it is not the one we are dealing with here. It is, however, unwise to expect ad hoc languages to exhibit great formal clarity. They do not much resemble explicitly designed statement-level procedural languages. They are much more like the languages we speak: They are not innocent of grammar, but they do often contain unholy mixtures of several grammars. John Gilmore, Ashland, MA 01721 - USA Avant d'imprimer cet e-mail, réfléchissons à l'impact sur l'environnement. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
