"Ts'il?os Park (a.k.a. Ts'yl-os Park) " established per Order in Council 0064, 12 January 1994, containing 233,240 ha. more or less. Conversion of OIC to Statute designation per Bill 53: Park Amendment Act 1995, 13 July 1995. Form of name changed to Ts^ 'il?os Park (ie. to add a circumflex ^ over the first s) per Bill 29: Park Amendment Act 1997, 23 July 1997, as requested by the Xeni Gwet'in First Nation. Form of name changed back to Ts'il?os Park as defined in Bill 50-2004: Parks and Protected Areas Statutes Amendment Act, 17 May 2004. Spelling confirmed August 2010 by BC Parks.

Source: BC place name cards, files, correspondence and/or research by BC Chief Geographer/Geographical Names Office.

A Chilcotin orthography has been devised by linguists, containing special characters that are not readily reproduceable, hence the writing system is undergoing rapid modification by writers of the language: "Ts^'il?os" ....where the first "s" is presented with a circumflex to modify the sound of the vowels that follow, the apostrophe denotes a glottal stop, and where the question mark is presented without the dot and also denotes a glottal stop. The common pronunciation, resulting from the alternate spelling appearing in print, is "SIGH-lows" or "SIGH-loss".

Source: BC place name cards, files, correspondence and/or research by BC Chief Geographer/Geographical Names Office.

Spelled Ts'il?os Park (a.k.a. Ts'yl-os Park) when established per Order in Council 0064, 12 January 1994;
Spelled Ts^ 'il?os Park per Bill 29: Park Amendment Act 1997, 23 July 1997;
Spelled TSIL?OS PARK in Bill 17-2000: Protected Areas of British Columbia Act, 29 June 2000;
Spelled Ts'yl-os Park on BC Parks website (February 2002);
Spelled Ts'il?os Park in Bill 50-2004: Parks and Protected Areas Statutes Amendment Act, 17 May 2004;
Spelled Ts'il?os Park on BC Parks website (June 2010).

Source: BC place name cards, files, correspondence and/or research by BC Chief Geographer/Geographical Names Office.

Ts'il?os is the name of the mountain that dominates the landscape east of Chilko Lake [formerly named "Mt. Tatlow"]; the mountain is an important spiritual site where a man named Ts'il?os was transformed to stone; he watches over and protects the Xeni people even today. See BC Parks website for an encapsulation of the Legend of Ts'il?os.

Source: BC place name cards, files, correspondence and/or research by BC Chief Geographer/Geographical Names Office.

See Tŝ'ilʔoŝ (mountain) for more information on the name origin.

Source: BC place name cards & correspondence, and/or research by BC Chief Geographer & Geographical Names Office staff.