n have one of the following
values: 
<TABLE BORDER="1" CELLSPACING="0" WIDTH="66%">
	<TR>
		<TH WIDTH="13%" BGCOLOR="#DDDDDD">Value</TH>
		<TH BGCOLOR="#DDDDDD">Description (click for variable format)</TH>
	</TR>
	<TR>
		<TD WIDTH="13%">00h</TD>
		<TD><A HREF="vars.html#expr">Expression</A></TD>
	</TR>
	<TR>
		<TD WIDTH="13%">04h</TD>
		<TD><A HREF="vars.html#list">List</A></TD>
	</TR>
	<TR>
		<TD WIDTH="13%">06h</TD>
		<TD><A HREF="vars.html#matrix">Matrix</A></TD>
	</TR>
	<TR>
		<TD WIDTH="13%">0Ah</TD>
	