Object sys contains some general-purpose constants and methods:

sys.lf Line feed character (\n)
sys.cr Carriage return character (\r)
sys.tab Tab character (\t)
sys.space Space character ( )
sys.quot Double quote character (")
sys.apos Single quote character (')
sys.backspace Backspace character (\b)
sys.date() Returns current date in the yyyyMMdd format
sys.time() Returns current time in the HHmmss format
sys.datetime(format) Returns date/time in specified format (Java date and time formatting patterns must be used).
sys.escapeXml(text) Escapes characters &'"<> in the specified text according to XML standard.
sys.fullUrl(pageUrl, link) For the specified URL of the web page and specified link (which could be relative, absolute or full URL) returns full URL.
sys.defineVariable(varname, varvalue, [overwrite]) Defines new variable with specified name and value in the current Web-Harvest context. Parameter overwrite tells whether to overwrite existing variable with the same name. Its default value is true. It has the same meaning as var-def processor, however it could be useful for value exchange between scripts and Web-Harvest context.
sys.isVariableDefined(varname) Tells if variable with specified name is defined in the context.
xpath(xpathexpr, xml) Evaluates XPath expression on specified XML. Returns instance of org.webharvest.runtime.variables.Variable class.