During the conversion to html I get:

jade:/home/manu/documents/manuel/TEmanual.sgml:727:18:E: document type does not allow element "INLINEMEDIAOBJECT" here; missing one of "REMARK", "SYNOPSIS", "LITERALLAYOUT", "PROGRAMLISTING", "SCREEN", "PARA", "SIMPARA", "BRIDGEHEAD" start-tag
jade:/home/manu/documents/manuel/TEmanual.sgml:735:22:E: end tag for "INLINEMEDIAOBJECT" which is not finished

What's in the sgml:

<inlinemediaobject><![ %output.print.png; [
<imageobject><imagedata fileref="&graph1001;.png"  scale="40"  format="png"></imageobject>
]]><![ %output.print.pdf; [
<imageobject><imagedata fileref="&graph1001;.pdf"  scale="40"  format="pdf"></imageobject>
]]><![ %output.print.eps; [
<imageobject><imagedata fileref="&graph1001;.eps"  scale="40"  format="eps"></imageobject>
]]><![ %output.print.bmp; [
<imageobject><imagedata fileref="&graph1001;.bmp"  scale="40"  format="bmp"></imageobject>
]]></inlinemediaobject>