Presumably Arcanu[s is to be restored, to agree with miles. Arcanus is registered as a cognomen in RNGCL; it probably occurs as such in 333 and it may well be a name here; on the other hand, if that were the case, we might expect the words in the reverse order. The only use we have found of the word arcanus in a military context is in Ammianus 28.3.8, where he describes military spies or secret agents: inter haec tam praecipua, arcanos [the ms. reading is areanos] genus hominum a ueteribus institutum ... a stationibus suis remouit ... id enim illis erat officium, ut ultro citroque, per longa spatia discurrentes, uicinarum gentium strepitus nostris ducibus intimarent (cf. Mann (1974), 40, note 50). Activities of this sort are certainly attested earlier (see P.Mich.VIII 469.24 note (= CEL 144), ChLA I 7 = RMR 9.15.e, Rankov (1987), 246 and cf. 164, introduction) and it is noteworthy that Ammianus describes the arcani as a longstanding institution. If this were the meaning of the word in the Vindolanda text it would not make its purpose any clearer; could it be an "identity card" carried by someone moving around the countryside in "plain clothes" (pagano cultu, cf. RMR 9.15.e) to be produced if he were challenged by other Roman military personnel?