It has come up often now that DFDL cannot be strict enough about text number formats because our ICU-based textNumberPattern isn't strict enough or expressive enough of subtle syntax variations. I suggest this could be fixed by just allowing the XSD pattern facet to be used on numeric types when they are known textual and standard (not zoned). For example dfdl:textNumberPattern="00.####" will allow the number "99." to be accepted. There's currently no way to say "when it's an integer, there cannot be a decimal point". People are resistant to the notion that this requires a complex type with a bunch of different elements with different textNumberFormats so that you have an '<int>99</int>' or <dec>99.9</dec> element. They really don't want there to be different paths to this value in the infoset just because of this format issue about the decimal point. It's a painful loss of polymorphism in these path expressions. Instead of a simple path expression to obtain such a value you end up with if (fn:exists(path/int)) then path/int else path/dec Note that DFDL's expression language has no let statement, so in the above if "path" is actually "a/b/c/d/e/f/g" i.e., a typical deep path (which commonly have much longer path steps than my single-letters), then that path is going to be repeated 3 times in the expression. This is pretty unpleasant. Rather than come up with a bunch of ICU mods to tighten up all the places it is lax, and to add features for suppressed decimal points, etc. we could just allow the pattern facet on textual numbers. Then the pattern facet could be "\d\d|\d\d\.\d{1,4}" which would achieve the goal of enforcing the precise pattern desired if you validate after parsing and before unparsing. It would not prevent conversion of the text to the corresponding numeric type, but it would allow an additional tighter check on what the text was. Regular XML Schema allows the pattern facet on all the numeric types, so we would be eliminating what is currently a DFDL restriction, on condition of only when the numeric types have standard text representation. Thoughts? Mike Beckerle Apache Daffodil PMC | daffodil.apache.org OGF DFDL Workgroup Co-Chair | www.ogf.org/ogf/doku.php/standards/dfdl/dfdl Owl Cyber Defense | www.owlcyberdefense.com