In XSLT, the rules are called as template rules. A template rule is an instruction to transform a specified source element in a particular way. To transform a set of data, you must provide a complete set of rules. However, each rule is independent of every other.
The order in which rules are declared (or executed) is not significant.
The XSLT processors put the XML document and XSLT style sheets together as data and code, and invoke template rules to produce the desired output.