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Asked: 2026-06-09T02:29:24+00:00

I am having a hard time figuring out this XSD Regex match. Here is

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I am having a hard time figuring out this XSD Regex match. Here is the simpleType defininition:

  <xs:simpleType name="data-fuelcorrfact">
    <xs:restriction base="xs:float">
      <xs:pattern value="\-?[1-9]\.[0-9]{4}"/>
    </xs:restriction>
  </xs:simpleType>

I can guess that it needs a number between 1 and 9, a period, and another number betwen 0 and 9. I don’t understand what the \-? is and putting a value of 1.0 for example fails validation.

Can someone please help me decipher this regular expresion? Also, does anyone have any references for programs or websites that can explain a given XSD regex value should consist of? Thanks!

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1 Answer

  1. Editorial Team

    I’m not familiar with XSD, but assuming that is uses the usual RegEx rules, here’s the breakdown:

    First, \-?. That matches one or zero dashes, i.e. negative or not. The \ is just an escape character, i.e. treat the - as an actual - character and not a special RegEx character. Outside of square brackets, though, it doesn’t usually have any special meaning. Might be an XSD thing.

    Next, [1-9] matches any non-zero numeral character (i.e. 1, 2, 3, 4, 5, 6, 7, 8, or 9). So a single-digit number.

    The \. does, in fact, match a period.

    Then we have [0-9]{4} which matches exactly 4 numeral characters (including zero now).

    So it’s looking for any number in (-10, 10) but not in (-1, 1) with exactly four decimal places. Strange behavior; I suspect the [1-9] should be [01-9] because it’s very weird to omit the values around 0 like that.

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