Page 30, Column 3, Paragraph(s) 4, Core Rule Book
Effect: The resolution of a card ability.

A game effect is any type of resolution of an ability, rules, or card text, as it pertains to some sort of change in the game state.

FAQ 1.3.20Edit

From the FAQ. Also numbers 1.4.20 and 1.5.19

Any choices necessary for a card effect are made by the player who owns the card unless directed otherwise.

Page 10, Column 1, Paragraph(s) 7, FAQ
The Runner does not break a subroutine that specifies "Trash 1 program." Who chooses the program to trash?
The Corp chooses which program to trash. Unless otherwise noted, each player makes the choices required by the effects on his card.
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