Oxygen XML WebApp automatically checks the document for errors. The errors and warnings
reported by the validation engine include problems found in the following:
- The structural integrity and well-formedness of the document.
- A set of best practice rules (such as a maximum number of words in a paragraph).
The automatic validation errors appear underlined in red, while warnings underlined in yellow. On the desktop version, if you hover the mouse over the errors or warnings, a tooltip is displayed that provides more information about the problem.
To see a detailed list of errors, tap or click the 
Validation
Results button on the upper toolbar (note the red marker that shows the number
of errors found in the document). Every item in the list has an arrow button to its right
side. Tap or click that button to go to the location in the document where the issue was
found.