# Search for Sequences |  | Back | Contents | Next |
| A specific sequence can be found by typing a sequence string position into the Find Sequence box and hitting return or enter. Each time return or enter is hit, the next sequence matching the pattern is highlighted. When no more matches are found, a dialog indicates this fact and the next time return or enter is hit, the search starts over from the beginning of the sequence. Hitting shift return or shift enter performs the search in the reverse direction. To extend the search pattern beyond simple text matching, a regular expression can also be entered. Regular expressions (also called regexes) use special characters like “.”, “*”, “|”, and others to expand search terms and match complicated queries. For example, the expression “ATG((?!TAG|TAA|TGA)...)+(TAG|TAA|TGA)” can be used to find open reading frames. For more information see http://www.regular-expressions.info/ and other websites. Searches are “greedy” meaning that the longest string that fits the regular expression will be found. |  |
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