Definition
Tense serves to relate the event time to the utterance time. (Ritter & Wiltschko, 2014, p. 1339) In Halkomelem, two of the non-personal second-position predicate particles mark tense, -əł ‘past’ and ceʔ ‘future’. (Suttles, 2003, p. 43) In Skwxwu7mesh, two important particles represent two tense morphemes: -t — past tense and ek’ — future tense. Both have variable syntax. While the past tense morpheme often seems to be optional, unless required to disambiguate, the future tense morpheme seems to be almost obligatory. (Jacobs, 2011, p. 87-88)
Examples

References
Suttles, W. (2004). Musqueum reference grammar. UBC Press. SFU Student Access.