What would the DTD syntax be for alpha or numeric data only?
There is no “best way.” One suggested mechanism is based on POSIX. Another mechanism is based on using URLs to trigger Java lextype analyzers (e.g., ) Other mechanisms based on the use of XSL can also be demonstrated. Alternatively, you can adopt the general-purpose mechanisms defined in ISO 10744 for defining lexical models using SGML. Or, you can say “ANSI ASC X12 messages conform to these data types” and require the use of parameter entities to define this. Here is yet another solution:
