Matthew Poole and continuators on Revelation 13:17

17 And that no man should either buy or sell, save he that had the mark, or the name of the beast, or the number of his name .

There have been great disputes about the Name and Number of the Beast. I must profess my self not able to distinguish betwixt the Mark Name, and Number of the Beast, they may all signify the same thing, viz. the Profession of the Romish Religion. Some think the Number is contained in the Name, and that the Name is ΛΛTEINOΣ, in which the Number 666 is contained; of which we shall speak more by and by.

This the Popish Church effects by its Excommunications; it was begun in the Councel of Lateran, anathematizing all who entertained any of the Waldenses, or traded with them; and the late learned Bishop of Armagh, in his Book de Successione Ecclesiae, hath given us an account of such a Canon of a Synod in France, which in express terms forbad any Commerce with Hereticks in buying or selling. Paraeus tells us Pope Martin the Fifth hath best interpreted this Prophecy, in his Bull added to the Council of Constance, where he prohibits Roman Catholicks, to suffer any Hereticks to have any Dwellings in their Countreys, or to make any Bargains, or use any Trades, or to perform to them any Civil Offices.

Marginal references: Chap. 14.11.