Is there an action cost for changing facing?

Question

Is there, in canonical D&D 3.5*, a ruling prescribing action (move action, standard action etc.) for changing the facing of a character without changing position, or a ruling specifically saying that it does not cost points (i.e. does count a free, or not at all as, an action)? If so, in which rule book or supplement are they?

Example: Can a character, according to the standard rules, change facing in his turn even if he has already expended all move and combat action capacity he got in it, e.g. in order to enable a flanking bonus on a different creature than the one which he just attacked and was facing for that purpose?

Also, are there in the canonical rulings differences in such prescriptions, if any, regarding the size category of characters? (I'd guess a giant would take longer to turn around than a human, even more so a large dragon, and at least with such the amount of time it would take would be a non-negligible factor.)

[EDIT: rulings included in respective literature as "variant" are also asked for]

*by "canonical" I mean the game rulings as they are prescribed in the rule books and supplements authorised or published by Wizards, in case of conflict: counting "core" content (core rule books, their extensions and other stuff by Wizards members/employees themselves) before so-to-speak "expanded universe" content (other publishers but also authorised with D&D/d20System license) in case of conflict

Answer 1

Through inference, there is no action cost for controlling facing.

The SRD presents a combat facing "add-on" that states:

The standard d20 combat rules intentionally ignore the direction a creature faces. The rules assume that creatures are constantly moving and shifting within their spaces, looking in all directions during a fight. In this variant, facing—the direction your head and body are pointing—makes a big difference in how you move and fight.

Given that the term appears nowhere else in the SRD, we can take the above description of the normal rules as true, and conclude that there is no cost, in normal 3.5, to "change" ones facing, as it is never measured.