ebnf.assignment — The EBNF production assignment operator
<xsl:param name="ebnf.assignment">
<fo:inline font-family="{$monospace.font.family}">
<xsl:text>::=</xsl:text>
</fo:inline>
</xsl:param>
The ebnf.assignment parameter determines what
text is used to show “assignment” in productions
in productionsets.
While “::=” is common, so are several
other operators.