An Introduction to Computer Searching of
Chemical Abstracts
STN International Version

Truncation & Character Masking Symbols

Symbol	Definition	Search	Retrieve
?	Any number of characters to the right of the term. Use only at the beginning or end of a term.	ALUM	ALUM ALUMINA ALUMINUM, etc.
!	Exactly one character at the designated position; multiple symbols can be used. Use anywhere except the beginning of a term.	THERMOLYS!S	THERMOLYSIS THERMOLYSES
#	One character or no character at the designated position; multiple symbols can be used. Use only at the end of a term.	CASEIN# METAL##	CASEIN CASEINS METAL METALS METALLIC