On Thu, Apr 2, 2020 at 12:46 PM Michael Kay mike@xxxxxxxxxxxx
<mailto:mike@xxxxxxxxxxxx> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:

Surely the error message is pretty clear?

See https://www.w3.org/TR/xmlschema-2/#duration

    B'3.2.6.1 The values of the Year, Month, Day, Hour and Minutes
    components are not restricted but allow an arbitrary unsigned
    integer, i.e., an integer that conforms to the pattern |[0-9]+|

The reference from spec you're citing might be explaining the error I
got. But I'm surprised, that

<xsl:variable name="dt1" select="xs:dayTimeDuration('PT5H')"/>
<xsl:value-of select="$dt1 div xs:dayTimeDuration('PT2H')"/>

doesn't give me an error.

but, following

<xsl:variable name="dt1" select="xs:dayTimeDuration('PT5H')"/>
<xsl:value-of select="$dt1 div xs:dayTimeDuration('PT2.5H')"/>

gives me an error.