Hello,
I had a closer look to the BNF expressed in this CR.
It will allow expressions like:

template charstring t_c1 := "ABC" & pattern "DE*"

is such a construct valid and if yes and how should the resulted template be
treated: as charstring or as a pattern?
Excluding CharstringMatch as an alternative from SimpleTemplateSpec and
inserting it as a direct alternative into the SimpleSpec production would make
more sense to me as CharstringMatch already incorporates the concat operation:

124. CharStringMatch ::= PatternKeyword Pattern {"&" (Pattern |
ReferencedValue)}

BR.,
Uwe Truetsch