These output tests verify conformance with the specification by recording that data and comparing it with what is required for conformance with the XML 1.0 specification.
At this writing, the OASIS output tests have several categories of known omissions (or weak output test coverage).
That error is either a conformance bug, or an error in the diagnostic being produced; or, rarely, both.
Nonvalidating processors may skip some tests if the tests require processing a class of external entities (general, parameter, or both) which that processor is known not to handle.
Other such comments may indicate other categories of conformance issue.
For example, some errors relate to problematic implementation of SAX; and in exceptional cases, the harness can be forced to report a failure on some test.
These include: Note that output tests automatically fail in cases where the processor failed to parse the (valid) input document used to generate the output data.
In some test harnessses, the output tests are unreliable because they can't directly compare the parser output against reference data.
HTML hides many such differences (because it normalizes whitespace before displaying it), and the method used to display the differing results may also mask some issues.
In all cases, negative tests that appear to pass (diagnostics presented with a white background) must be individually examined in the report below.
The diagnostic provided by the processor must correspond to the description of the test provided; if the processor does not report the matching error, the seeming "pass" is in fact an error of a type the test harness could not detect or report.
The diagnostic was reported as a recoverable error.
Such errors primarily used to report validation errors, which are all violations of validity constraints, but some other errors are also classed as nonfatal.