Post by Nemo Post by Christoph Schlegel
Guess you found an accidental omission -
Indeed. Railroad diagrammes were introduced in PIM3, which is also
Not the first time that I found something "accidental", but never mind.
Meanwhile, I have generated diagrams for PIM4 and put them on a page at:
Speaking of accidents, the diagram for Variant seemed wrong to me when I created it. It has a bypass which permits Variant to be empty. Not only is it bad practise to have empty productions in a grammar, but it is also nonsensical, allowing any number of occurrences of | in a variant field list.
But I checked the diagram in the annex of the book and it clearly has that bypass. I didn't check then against the EBNF, but now that I look at the result, I did and the EBNF does not permit Variant to be empty, so the diagram in the annex is wrong. I will fix the diagram on the wiki later. Naturally, I can't fix it in the book, but Springer have only recently re-released the book, I bet they still have the errors in there. I guess I should write them a mail.