This causes a warning when accidentally backpatching an XML-style
empty-element tag like <xref linkend="abc"/>.
# Enable some extra warnings
# -wfully-tagged needed to throw a warning on missing tags
# for older tool chains, 2007-08-31
-override SPFLAGS += -wall -wno-unused-param -wfully-tagged
+# -wnet catches XML-style empty-element tags like <xref linkend="abc"/>.
+override SPFLAGS += -wall -wno-unused-param -wfully-tagged -wnet
# Additional warnings for XML compatibility. The conditional is meant
# to detect whether we are using OpenSP rather than the ancient
# original SP.