[xsl] Grouping in match patterns

["Wendell Piez wapiez@xxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

XSL-List friends,

Is there anything special I should know about a match pattern such as
"a / (b|c)" -- which gives me an error (in oXygen and running Saxon)?

<xsl:template match="a / (b | c)"/>

Wouldn't it be permitted by the grammar given at
https://www.w3.org/TR/xslt-30/#pattern-syntax? Production [11] would
seem to permit a parenthetical expression as a discrete step. Is there
something I am missing here?

While it's easy enough to write "a/b | a/c", in the real world, this
isn't quite my case -- the pattern is machine-generated and the paths
are potentially complex, such as (a simple case with only two
branches):

j:map[@key='ANTHOLOGY']/j:map[@key='meta']/ (
j:array[@key='keywords']/j:string | j:string[@key='keywords'] )

Thanks for any insights --
Wendell

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