Kieperr said:
Sunder, Grapple, Trip, and Disarm are all melee attacks.
From the PHB:
Disarm: As a melee attack, you may attempt to disarm your opponent.
Grapple: Starting a grapple requires a successful melee attack roll.
Sunder: You can use a melee attack with a slashing or bludgeoning weapon to strike a weapon or shield that your opponent is holding.
Trip: You can try to trip an opponent as an unarmed melee attack.
Of all four only Sunder is listed under Standard Action on the Actions in Combat table. The other three are listed under Action Type Varies and have the footnote that allows them to be used multiple times. Only Grapple states that you can make multiple attempts to start a grapple if you have multiple attacks. There is nothing in any of the descriptions that define whether or not these special attacks are standard actions. That is what the table does. There is no discrepancy between the table and the descriptions of these special attacks. They all require a melee attack but that does not mean that they can all be attempted multiple times per round. Sunder is defined as a standard action and as such cannot be attempted more than once per round.
You forgot a couple more
Bull rush: You can make a bull rush as a standard action (an attack) or as part of a charge (see Charge, below.)
Overrun: You can attempt an overrun as a standard action taken during your move.
Aid Another: If you’re in position to make a melee attack on an opponent that is engaging a friend in melee combat, you can attempt to aid your friend as a standard action.
These are all under the same section as Sunder, Disarm, Grapple and Trip. Yet they cleary say they take a Standard action to perform.
CMIIAR, but a melee attack can be taken in many different situations. As a Standard action, as a Full round action, as part of a Charge, as part of an Attack of Opportunity (not an action) just to name a few. Melee attacks are not limited to Standard Actions only. However... if you take a Standard Action, you ARE limited to making 1 melee attack.
So, according to the text (not the table), the actions (Trip, Sunder, Disarm, etc.) listed as melee attack should be able to be taken anytime you make a melee attack. According to their text description they aren't limited other than to the amount of times a melee attack would apply. For Bull rush, overrun and aid another, you have to specifically take a Standard Action to use them. Which in turn has to be a melee attack. Which in turn is limited to once per round.
Now the tables are there not to correct or clarify what the text says, but to make a nice and neat one-stop section where you can go to look up some rules. They are there so you don't have to thumb through the entire combat section looking to see if Disarm provokes an AoO or if Charge is a full-round or standard action. The table is all of a sudden adding a limitation to Sunder, which is that it takes a Standard Action to perform, which means only once per round. If you look at the text alone, you would never know this. This limitation (and confusion) is created due to the table. Which very well may be what the intent is (or not). The problem is, some people here are arguing that they mean the same thing. I don't see it.
This also has the added side effect that you can't Charge and Sunder someone's shield/weapon using the attack from Charge. Just something to note.
As far as the footnote... Obviouly IF the table is wrong, the footnote is wrong.