PHP markdown not handling URL with parenthesis e.g. _(programming) in DBPedia link

[ross-spencer]

[<xsl:value-of select="rdfs:seeAlso/@rdf:resource"/>](<xsl:value-of select="rdfs:seeAlso/@rdf:resource"/>)

Link we want to return: http://dbpedia.org/page/Magic_number_(programming)

Can find it is correct via SPARQL: describe http://the-fr.org/prop/format-registry/hasPRONOMBinaryMagic

n.b. not handling underscores either!