Most regiments carried a number and a name (normally a peregrini tribal name) e.g. I Raetorum. A few regiments had no number. A confusing aspect of auxiliary unit nomenclature is that in some cases, more than one regiment can appear in the record with the same number and name e.g. there are two I Raetorum units attested in the 2nd century. In a few cases there is dispute as to whether it really is two distinct regiments, as opposed to the same regiment moving from one province to another or two detachments of the same regiment in different provinces at the same time. But in most cases, there is no doubt two separate regiments are involved. They can usually be distinguished by whether one is equitata or not, or has a c.R. title or not e.g. I Raetorum and I Raetorum c.R.