Looks like ICU changed behavior.... From: Steve Lawrence <slawrence@apache.org> Sent: Thursday, August 29, 2019 1:30 PM To: users@daffodil.apache.org Subject: Re: Plus '+' sign and lax textNumberCheckPolicy - was: Re: How to model a fixed-length integer that may be padded with space on the left? I think this is a difference in ICU version? A little grepping through ICU source, I found a change [1] to their number parsing logic in Dec 2017: + if (!isStrict) { + parser.addMatcher(WhitespaceMatcher.getInstance()); + parser.addMatcher(new PlusSignMatcher()); + } That looks to me like a change to make it so plus signs are always matched in lax/lenient mode regardless of the pattern (Daffodils current behavior). A couple minor changes have been made to that section, but nothing that allows you to turn if off if lenient is on. It's hard to tell in the git history what release that was in, but it looks like around version 61, which is relatively new (Daffodil is on version 62). Also, the latest version of DecimalFormatProperties.java (looks to be an internal implementation, so no online javadocs), has javadocs that states that plus signs are always allowed in lenient/lax mode [2]. I think this is a change in ICU behavior in newer versions. - Steve [1] https://github.com/unicode-org/icu/commit/68340c8464bd988477d6c88f46f9dfe456... [2] https://github.com/unicode-org/icu/blob/master/icu4j/main/classes/core/src/c...