From CUU website:

Option Agreement: Pursuant to a 2002 Option Agreement with Teck, Copper Fox has acquired a 100% working interest in the Schaft Creek Project (subject to a 3.5% net profits interest held by Royal Gold, Inc., a 30% carried interest held by Liard Copper and an earn back option held by Teck Resources Limited ("Teck") Under the terms of the 2002 option agreement with Teck, Copper Fox can earn their 78% interest, or 23.4 % of the deposit, by completing a "positive" Feasibility Study. Pursuant to the Option Agreement, Teck may at any time elect to exercise its earn-back rights, on receipt of a Positive Bankable Feasibility Study, a defined term in the Option Agreement, Teck has 120 days in which to elect to either: i) exercise one of its earn-back options, or ii) retain a 1% net smelter return royalty, or iii) receive shares of Copper Fox to a value of $1,000,000.

...so I undersand the "positive" is a term defined in the Option Agreement.

I'll go read that now.