Is xsd a reserved namespace for xpath?

If I have an XML like the following:

  [tt:181c4ich]
    123
  [/tt:181c4ich]

and I do a property expansion to get a node like so

  [tt:181c4ich]context.expand('${Properties#xml#//xse:c[1]/text()}')[/tt:181c4ich]

I get 123.

However if I use 'xsd' as the namespace prefix

  [tt:181c4ich]
    123
 
 [/tt:181c4ich]

and apply the appropriate expansion

  [tt:181c4ich]context.expand('${Properties#xml#//xsd:c[1]/text()}')[/tt:181c4ich]

I get no result.