Table 1.

Basic rules used in strategies

Rule	Example
FL: A letter of SF matches the 1st letter of a worda in LF.	Letter
FC: A character of SF matches the 1st character of a word in LF.	1-word
FCG: A character of SF matches the character following a non-alphanumeric non-space character in LF.	Word-Word
LS: The last character of SF is 's' and matches the last character of LF 's'.	Words
NF: A character of SF matches any character except the 1st character in LF.	Word, Word, Word
SBW: A character of SF matches a character within a word in LF and the substring of that LF word from the match until the end of the word is a defined wordb.	WordWord
CL: A substring of SF matches any two or more consecutive characters of a word in LF.	Word, Word, Word
ST: While matching SF with LF, skip a stopword in LF.	Stopword
SK: While matching SF with LF, skip a word in LF.	Word
AC: A character of SF matches any character in LF	Word, Word, Word, Word

^a Words are white space demarcated strings. This applies to all rules.

^b A defined word is at least three letters, a non-stopword, and appears at least 100 times in MEDLINE.