Xslt

Two or more templates match the same node with equal priority. Saxon warns (or errors in strict mode) and picks the last one declared — make the intent explicit.

An XSLT element appears somewhere the language grammar does not allow: wrong nesting, wrong order, or content at the stylesheet top level that must live inside a template.

Two xsl:variable or xsl:param declarations with the same name exist at the same level — often caused by a stylesheet being included twice.

An honest comparison of the free online XSLT testers that actually support XSLT 3.0 — Saxon HE vs Saxon-JS, multiple inputs, validation and trace. Which to pick and why.

How to use xsl:result-document in XSLT 2.0 and 3.0 to produce multiple output files from a single stylesheet. Covers split by category, multi-format output, serialization control, and streaming.

Returns the value of a named accumulator computed after processing the current node in streaming mode.

Returns the value of a named accumulator computed before processing the current node in streaming mode.

Returns a new array containing only the members for which a predicate function returns true.

Recursively flattens nested arrays into a single flat sequence of atomic items and nodes.

Accumulates a result by applying a function to each array member from left to right, starting with a seed value.