XSH commands accept different types of arguments, such as usual strings (expression) or XPath expressions. Notably, these two types and types based on them support string variable interpolation. See documentation of the individual types for more information.
single XSH command or a block of XSH commands
character encoding (codepage) identifier
relative destination specification (such as after, before, etc.)
node type specification (such as element, attribute, etc.)
in-line code in Perl programming language