If the parser is unable to find a complete linkage for a sentence - one which links all the words together according to the requirements of the words - it begins to use "null-links". It begins by trying to parse the sentence, ignoring one word. It will find all possible ways of parsing the sentence in this way. This is "null count 1". If no linkages are found, it will try again, this time ignoring two words; this is "null count 2". It will continue to increment the number of null links until it finds a valid linkage. The words being ignored are surrounded by square brackets.