The lcMatchingPair element was deprecated in DITA version 1.3. It was replaced with the lcMatchingPair2 element. It was originally intended to provide a table row with the pair of items that comprise a correct match in a matching interaction and, optionally, feedback on the pair or correct and incorrect matches.
+ topic/strow learningInteractionBase-d/strow learning-d/lcMatchingPair
... <lcMatchingPair> <lcItem>Boston</lcItem> <lcMatchingItem>Red Sox</lcMatchingItem> <lcMatchingItemFeedback> <lcFeedbackCorrect>The Red Sox play in Boston's Fenway Park</lcFeedbackCorrect> <lcFeedbackCorrect>That is not Boston's home team</lcFeedbackCorrect> </lcMatchingItemFeedback> </lcMatchingPair> ...