Variable HTML Escape Syntax

Normally, variables printed directly via $var may or may not be HTML-escaped, depending on the current htmlmode (here). To force a given variable to be HTML-escaped regardless of htmlmode, in (syntax) version 8 and later it may be printed as $+var; to force no HTML-escapement, $-var. These syntaxes may be useful when printing a variable in an unknown htmlmode context, or that is known to already be HTML-escaped. These flags may not be given to variables in a non-printing context, e.g. when passed as parameters.