Character entity references can also have the format &name; where name is a case-sensitive alphanumeric string. For example, Î» can also be encoded as &lambda; in an HTML document. The character entity references &lt; , &gt; , &quot; and &amp; are predefined in HTML and SGML, because, ,  and & are already used to delimit markup. This notably does not include XML's &apos; (') entity.
Lack of facial expression. Lack of facial expression: Introduction. An absence of expression on the face is medically called flat affect. In many cases, the face mirrors the underlying emotions, and the person has limited emotions or various emotional or psychological disorders.
There are two brain pathways associated with facial expression; the first is voluntary expression. Voluntary expression travels from the primary motor cortex through the pyramidal tract, specifically the corticobulbar projections. The cortex is associated with display rules in emotion, which are social precepts that influence and modify expressions.