Table 1.

List of various features for the concept task

Category	Features
Lexical context features	The target itself (n-gram)
Syntactic context features	The POS
	The phrases of NPs and APs
Ontological features	UMLS-based dictionary matching
	MeSH-based dictionary matching
	Medication dictionary matching
	Head-noun dictionary matching
Sentence features	The sentence with a dosage-unit or temporal adverb (eg, twice daily or q4h)
	The sentence with numerals before dosage-units
	The sentence containing a drug name before a numeral
	The sentence with characteristics such as [the phrase] [numeral] [dosage]
	The sentence with a drug name followed by an alternative drug name in parentheses, eg, fosamax (alendronate)
Word features	Word capitalized
	Entire word capitalized
	Word abbreviation
	The phrase before the numerals
	Assertion word
	Body word
	Pattern matching
	Word normalization
	N-character-prefix-and-suffix
	Word clustering

AP, adjective phrase; NP, noun phrase; POS, part of speech.