First of all, the announcement speaks of the promulgation of an "Apostolic constitution." Wikipedia proves unusually helpful here. It explains that an Apostolic constitution (Lat. constitutio apostolica) "is the highest level of decree issued by the Pope of the Roman Catholic Church." As such it issues as a papal bull (named for the metal bulla with which such decrees were sealed in times past), with a Latin title and the beginning words (in the case of Benedict XVI): "Benedictus, Episcopus, Servus Servorum Dei . . . ["Benedict, Bishop, Servant of the Servants of God . . ."]. A papal bull, in turn, is a subclass (particular to the Pope) of what are called letters patent, which a government or monarch issues to confer certain rights, status and/or privileges upon a territory, organization or class of people.
So that is what the "Apostolic constitution" will do when it is issued: it will be a formal charter establishing the canonical terms and conditions upon which the "personal ordinariates" which it creates are to come into being and to continue to exist within the Roman Catholic Church. Now as to the personal ordinariates: they are an amalgam of two already existing structures in the canon law of the Church: personal prelatures and military ordinariates.
Personal prelatures were made a feature of the 1983 Code of Canon Law after they were established by Pope Paul VI following a recommendation by the Second Vatican Council. Here are the sections of the Code which deal with them:
PERSONAL PRELATURES (Cann. 294 - 297)
Can. 294 After the conferences of bishops involved have been heard, the Apostolic See can erect personal prelatures, which consist of presbyters and deacons of the secular clergy, to promote a suitable distribution of presbyters or to accomplish particular pastoral or missionary works for various regions or for different social groups.
Can. 295 §1. The statutes established by the Apostolic See govern a personal prelature, and a prelate presides over it as the proper ordinary; he has the right to erect a national or international seminary and even to incardinate students and promote them to orders under title of service to the prelature.
§2. The prelate must see to both the spiritual formation and decent support of those whom he has promoted under the above-mentioned title.
Can. 296 Lay persons can dedicate themselves to the apostolic works of a personal prelature by agreements entered into with the prelature. The statutes, however, are to determine suitably the manner of this organic cooperation and the principal duties and rights connected to it.
Can. 297 The statutes likewise are to define the relations of the personal prelature with the local ordinaries in whose particular churches the prelature itself exercises or desires to exercise its pastoral or missionary works, with the previous consent of the diocesan bishop.
As you see, personal prelatures are established by the Holy See "after the conferences of bishops involved have been heard." They have the inherent right to establish seminaries and to "incardinate" their students, i.e., place them under the jurisdiction of the prelate for later ordination and advancement. This will be a feature important to Anglo-Catholics, which is expected to be preserved in the creation of "personal ordinariates."
The only personal prelature to have been established to date is Opus Dei, the organization known (but poorly) to most people through the fiction of Dan Brown. Pope John Paul II created it by publishing the Apostolic constitution Ut sit in 1982 (the organization had been in existence since its formation in Spain in 1928; the Pope's bull elevated it into a personal prefecture). So that you can see what an "Apostolic constitution" looks like, here are the first six numbered paragraphs (and the last introductory paragraph) of the one that erected Opus Dei:
Now as to military ordinariates: Wikipedia has a list of the ones that have been established around the world. Though they are designated with respect to particular continents and countries, they do not have a geographical territory as such; in this respect they differ from the canonical definition of a diocese, a territorial prelature, and a territorial abbacy:
Therefore, We, with the plenitude of Our apostolic power, having accepted the opinion which Our Venerable Brother the Most Eminent and Most Reverend Cardinal Prefect of the Sacred Congregation for Bishops had expressed to Us, and making good, in so far as it is necessary, the consent of those who have, or think they have some competence in this matter, command and desire the following to be put into practice.
Opus Dei is erected as a personal Prelature, international in ambition, with the name of the Holy Cross and Opus Dei, or, in abbreviated form, Opus Dei. The Sacerdotal Society of the Holy Cross is erected as a clerical Association intrinsically united to the Prelature.
The Prelature is governed by the norms of general law, by those of this Constitution, and by its own Statutes, which receive the name "Code of particular law of Opus Dei".
The jurisdiction of the personal Prelature extends to the clergy incardinated in it, and also—only in what refers to the fulfillment of the specific obligations undertaken through the juridical bond, by means of a contract with the Prelature—to the laity who dedicate themselves to the apostolic activities of the Prelature: both clergy and laity are under the authority of the Prelate in carrying out the pastoral task of the Prelature, as established in the preceding article.
The Ordinary of the Prelature Opus Dei is its Prelate, whose election, which has to be carried out as established in general and particular law, has to be confirmed by the Roman Pontiff.
The Prelature is under the Sacred Congregation for Bishops, and will also deal directly with the other Congregations or Departments of the Roman Curia, according to the nature of the matter involved.
Through the Sacred Congregation for Bishops, the Prelate will present to the Roman Pontiff, every five years, a report on the state of the Prelature, and on the development of its apostolic work.
In contrast to these, the military ordinariates are a species of what the Code of Canon Law calls an "apostolic vicariate" or "apostolic prefecture" -- hierarchical structures without a defined territory under the control of an "apostolic vicar" or "prefect":
Can. 369 A diocese is a portion of the people of God which is entrusted to a bishop for him to shepherd with the cooperation of the presbyterium, so that, adhering to its pastor and gathered by him in the Holy Spirit through the gospel and the Eucharist, it constitutes a particular church in which the one, holy, catholic, and apostolic Church of Christ is truly present and operative.
Can. 370 A territorial prelature or territorial abbacy is a certain portion of the people of God which is defined territorially and whose care, due to special circumstances, is entrusted to some prelate or abbot who governs it as its proper pastor just like a diocesan bishop.
Can. 371 §1. An apostolic vicariate or apostolic prefecture is a certain portion of the people of God which has not yet been established as a diocese due to special circumstances and which, to be shepherded, is entrusted to an apostolic vicar or apostolic prefect who governs it in the name of the Supreme Pontiff.The Code goes on to provide for the creation of such structures only by the "supreme authority", i.e., the Pope:
Thus now you can begin to see how the Vatican has conceived of an amalgam of "personal prelatures" and "apostolic vicariates" to come up with "personal ordinariates." It is important to realize that, contrary to what you may have read in some accounts, there are as yet no personal ordinariates established anywhere in the world; there are only military ordinariates, and they are largely different, since their function is to provide pastoral care to Catholics who find themselves stationed temporarily outside the geographical boundaries of any established Catholic diocese. (Likewise, the Pastoral Provision decreed in 1980 for the United States is completely under the supervision of Catholic diocesans, who are regular members of the Catholic hierarchy.) The military ordinariates also have a hierarchical structure, in which the curates and chaplains report to a higher official, who in turn may report to a bishop or archbishop, but the latter may be very distant geographically.
Can. 372 §1. As a rule, a portion of the people of God which constitutes a diocese or other particular church is limited to a definite territory so that it includes all the faithful living in the territory.
§2. Nevertheless, where in the judgment of the supreme authority of the Church it seems advantageous after the conferences of bishops concerned have been heard, particular churches distinguished by the rite of the faithful or some other similar reason can be erected in the same territory.
Can. 373 It is only for the supreme authority to erect particular churches; those legitimately erected possess juridic personality by the law itself.
Can. 374 §1. Every diocese or other particular church is to be divided into distinct parts or parishes.
§2. To foster pastoral care through common action, several neighboring parishes can be joined into special groups, such as vicariates forane [Lat. for "deaneries"].
In contrast, according to the Vatican's announcement, the personal ordinariate has been envisioned as a geographically related entity whose "ordinary" will be in close proximity to those whom he supervises, in much the same manner as current Anglican dioceses are organized. However, because there are already Catholic dioceses which cover the entire geographical territory of, say, England, what the Pope proposes to establish to accommodate Anglicans cannot be dioceses in name, though it appears they will be close to them in structure and appearance.
And that brings up another fascinating question. The Church of England itself is not a single monolithic entity, but is an immensely complex conglomeration of individual parish corporations sole, trusts and other forms of property ownership which go back to the early Middle Ages. If you think American property law is complex, try delving into the many forms by which church property is owned and passed on in England. Parliament has tried from time to time to simplify the holdings through legislation, but no one legislative solution has worked, and the various laws and exceptions have served only to add still more layers of complexity. (At least that is my understanding the last time I looked at the matter, after enactment of the Pastoral Measure Code of Practice in 1983. You can download from that link as much as you would ever want to know about parish property in the Church of England.)
Thus, if Anglo-Catholics depart from the Church of England, there can scarcely be any question of their leaving with the local church property. If they organize as a personal ordinariate in a given English area, they will have to make provision for where they will gather for worship, and for how the salaries of their priests (and of the ordinary) will be paid. It will be like starting an entire church from the ground up. It appears that those are some of the problems which Forward in Faith/UK intends to address when it gathers this weekend -- note the discussion of individual and parish finances in the article.
Doubtless Archbishop Rowan Williams would have welcomed a somewhat slower pace of events. Benedict XVI is 82, however, and given that the Code of Canon Law leaves it all up to him, he is not about to wait for the Church of England (or the Anglican Communion, for that matter) to come to a single mind on issues of ecumenical concern -- especially under the painful sort of leadership with which ++Rowan appears to be most comfortable. It was a brilliant stroke on Benedict's part to decide to let the Anglo-Catholics sort things out for themselves under his papal aegis. Just as the departures of its dioceses and the formation of ACNA have left the Episcopal Church (USA) free to walk the path it has chosen for itself, so the departures of the Anglo-Catholics will leave the Church of England free to walk whatever path its remaining constituents can manage to agree upon.
As I discussed in my previous post, however, the prospects of agreement on any single course seem remote. After the CoE ordains women to the episcopate, the same-sex advocates will be sure to follow. Then what will become of the Anglican Communion and its Resolution 1.10 which ++Rowan has so resolutely protected? By then, as I noted, the Global South and GAFCON will have separated themselves from the rest of the Communion by a Covenant which the liberal majorities in both the CoE and ECUSA will refuse to approve (even if the CoE manages to remain an established church). At that point, we will have two separate Communions, and not a two-track one. [UPDATE 10/21/2009: Or will the Global South consider accepting Rome's invitation as well? The implications of that would be truly staggering for the Anglican Communion.]
Benedict and his canon lawyers have moved ahead of the curve with their proposal, while the Anglican Communion, ECUSA and the remnant CoE will all be behind it. ACNA is where the future will now be for traditional American Anglicans, because only it has the structural and organizational flexibility to adapt to the changing church tectonics. After some time, ACNA may branch off into separate parts, some of whom may (also in time) be able to organize personal ordinariates in order to affiliate with Rome. (Watch what happens over the next five years, for example, in Bishop Iker's diocese.)
No wonder there is so little relish for Benedict's plans shown by 815. Their future lies, if at all, still further from Rome, and perhaps in association with the liberals in the Church of England, as a greatly reduced "Anglican Transatlantic Communion" -- if they manage to stay solvent in the coming financial turmoil. (Now is not the time to be investing in vacant properties for sale.) ECUSA is going to get fully what it wished for when it consecrated the Rt. Rev. V. Gene Robinson.