xsl:expose has

[ERR XTSE3020] It is a static error if an xsl:expose element matches no components in the containing package, unless the tokens in the names attribute are all wildcards.

and xsl:accept similarly has

[ERR XTSE3030] It is a static error if an xsl:accept element matches no components in the used package, unless the tokens in its names attribute are all wildcards.

The means that if the attribute names="a b c" is used, it's OK provided at least one of a, b, or c exists in the relevant package. This seems to make little sense. I think the rule should be that any token that isn't a wildcard is required to match the name of a component in the relevant package. The rules should be rewritten thus:

[ERR XTSE3020] It is a static error if a token in the names attribute of xsl:expose, other than a wildcard, matches no component in the containing package.

and xsl:accept similarly has

[ERR XTSE3030] It is a static error if a token in the names attribute of xsl:accept, other than a wildcard, matches no component in the used package.