Can you shift 0 squares (and still be considered to have shifted)?

Question

The answer to my previous question (Does the Knight's Bladed Step require the shift to gain CA?) was based on the claim that you can shift 0 squares and still be considered to have shifted. However, the player who inspired the original post found that claim questionable, and I've been hard-pressed to disagree.

While we accept that you could simply choose not to make a shift granted by a power or feature, we couldn't find anything that explicitly allowed a 0-square shift that would still trigger other benefits you gain from shifting, such as the Knight's Bladed Step or the property on the Boots of the Fencing Master (both reprinted below). Do rules explicitly allowing a 0-square shift exist? This can be either the Shift basic action, or a power that allows shifting as part of using it, but if the rules only apply to one of these, please specify.

Bladed Step

Benefit: After you use power strike with a heavy blade, you can immediately shift 1 square to a square adjacent to an enemy. You then gain combat advantage against that enemy until the end of your next turn.

^{Heroes of the Fallen Lands, pg 136}

Boots of the Fencing Master

Property: When you shift, gain a +1 item bonus to AC and Reflex defense until the end of your next turn.

^{Adventurer's Vault, pg 127}

Note: While the description of the Walk action states "The creature moves up to its speed," implying a minimum of 0, the Shift action has no similar qualifier, simply stating "The creature moves 1 square," without the "up to."

Answer 1

Under the section Three Basic Rules on PHB 11:

Specific Beats General If a specific rule contradicts a general rule, the specific rule wins

Under the description of the Shift action on PHB 292 is a very general rule:

Movement: Move 1 square.

So, a Shift is moving exactly 1 square unless something else specifically says otherwise (for example, a power description). That is, there is no ambiguity or choice as in the phrases "up to one square" or "may move one square". Conversely, if you didn't move 1 square then you didn't Shift.

Thematically, suppose you're fighting in a narrow hallway and use Power Strike on an opponent. If you can't shift to the side and still be adjacent because of the walls, then the terrain has boxed you in and you can't use the technique to its fullest advantage.