As noted previously in this blog, in February 2007, the Democratic National Party published a "Call to the Convention". This document went out over Howard Dean's name in his capacity as Chairman of the Democratic National Committee after being adopted by the Committee on February 2.

The Call to the Convention serves as a blueprint or governance document specifying how the the convention will be convened and what will happen there. The first parts deal with how people other than superdelegates (or as they are officially called "automatic delegates) can qualify to become delegates to the National Convention. The later sections specify how the Convention is to operate.

Section VI defines the term "Presidential Candidate" for purposes of the Convention. Here is that provision in its entirety:

The term “presidential candidate” herein shall mean any person who, as determined by the National Chairperson of the Democratic National Committee, has accrued delegates in the nominating process and plans to seek the nomination, has established substantial support for his or her nomination as the Democratic candidate for the Office of the President of the United States, is a bona fide Democrat whose record of public service, accomplishment, public writings and/or public statements affirmatively demonstrates that he or she is faithful to the interests, welfare and success of the Democratic Party of the United States, and will participate in the Convention in good faith.

Note: the "plans to seek the nomination" does not state a deadline for when a candidate must announce that he or she so plans. So any candidate who meets the other guidelines in Section VI and announces prior to the convention's start that she or he is seeking the nomination qualifies as a "Presidential candidate" for purposes of the Call. As of today, July 25, Senator Obama is the only person who is in this position. As of August 1 or August 15 or August 20 (I'm just naming random dates before the start of the convention), others may have thrown their hat in the ring. John Edwards, for example, could do so.

An alternative mechanism by which a candidate can indicate that he or she seeks the nomination is by signing a nomination petition from the floor and this can be done up to the day before the relevant Convention proceedings. This is specified in a number of provisions from VIII. PROCEDURAL RULES OF THE 2008 DEMOCRATIC NATIONAL CONVENTION including subsection 6a:

6. Nomination of the Democratic Candidate for President: The Permanent Chair shall receive nominations from the floor for the Democratic candidate for the Office of President of the United States in the following manner:
a. Requests to nominate a presidential candidate shall be in writing and shall have affixed thereto the written approval of the proposed nominee and the name of the individuals who shall be recognized to make the nominating and seconding speeches on behalf of a presidential candidate and shall be delivered to the Convention Secretary at a location as specified by the Secretary no later than 6:00 p.m. of the day preceding the day designated for the commencement of presidential nominations.

Provisions 6(b)(c) and (d) specify the nomination process applicable to all nominees:

b. Each such request must be accompanied by a petition indicating support for the proposed nominee signed by delegates representing not less than 300 or more
than 600 delegate votes, not more than 50 of which may come from one (1) delegation. A delegate may not sign more than one (1) nominating petition for president and for vice president.
c. The order for nominating presidential candidates shall be determined by the National Chairperson of the Democratic National Committee, the Permanent Chair of the Convention and each presidential candidate, or his or her authorized representative, who qualifies to be nominated pursuant to this section.
d. Each presidential candidate shall be allowed a total of twenty (20) minutes for the presentation of his or her name in nomination by nominating and seconding speeches, the time to run without interruption from the recognition of the nominator.
e. Delegates and alternates shall maintain order during and following nominations for the Office of President and demonstrations shall not be permitted.

Finally, subsection 7 defines what happens after the nomination speeches are given:

7. Roll Call for Presidential Candidate:
a. After nominations for presidential candidates have closed, the Convention shall proceed to a roll call vote by states on the selection of the presidential candidate. The roll call voting shall follow the alphabetical order of the states with the District of Columbia and Puerto Rico and the territories treated as states for the purpose of the alphabetical roll call.
b. A majority vote of the Convention’s delegates shall be required to nominate the presidential candidate.
c. Delegates may vote for the candidate of their choice whether or not the name of such candidate was placed in nomination. Any vote cast other than a vote for a presidential candidate meeting the requirements of Article VI of this Call and Rule 12.K. of the 2008 Delegate Selection Rules shall be considered a vote for “Present.”
d. Balloting will continue until a nominee is selected. The nominee shall become the candidate of the Democratic Party of the United States for the Office of President upon the conclusion of his or her acceptance speech.

Note: it is because of subsection 7(c) that the difference between being a nominee and simply being on the ballot makes a difference. If a candidate is not a nominee at the time of the roll call, votes for that candidate simply count as "present".