Skills may be switched for other skills at the maximum rate of 1 every three weeks, to a minimum of 1 rank remaining. In adverse circumstances, the skill may only be switched at the rate of 1 every 6 weeks. The skill ,points are considered to come from the same class they are switched from.
Skill switching requires DM approval.
As an example of the first, a 9th level character could change a feat they selected they reached 12th level. If they were a fighter, they could not use their fighter bonus feat at 10th level to switch a general feat.
As an example of the latter, after 3 months a character could switch weapon focus from one weapon to another, or skill focus from one skill to another.
Feat changes will be scutinised more throughly than skill changes.