Fighting Defensively

[Abba]

From the Core Rulebook:

Fighting Defensively as a Standard Action

You can choose to fight defensively when attacking. If you do so, you take a –4 penalty on all attacks in a round to gain a +2 to AC until the start of your next turn.

When fighting defensively is it possible to make ONLY ONE attack?
In this assumption the phrase: "you take a –4 penalty on all attacks in a round" would apply only to opportunity attacks.

Am I wrong?

G. Luca

[Starglim]

"When attacking" includes making one attack (presumably as a standard action). You take a -4 to this attack. You also take a -4 to any attacks of opportunity you take until the start of your next turn.

[Remco Sommeling]

"Fighting Defensively as a Full-Round Action

You can choose to fight defensively when taking a full-attack action. If you do so, you take a –4 penalty on all attacks in a round to gain a +2 dodge bonus to AC until the start of your next turn."

So you can either make a single attack action or a full attack action as normal, either way you keep the penalty and benefit until the start of your next turn.