When the concession is stated as an admitted fact, the indicative is regular.

280. After if and unless, expressing condition, the subjunctive may be used in a variety of ways.

In conditional clauses, the present subjunctive denotes either present or future time. It puts the supposed case doubtfully, but not necessarily as improbable. (See examples 1–3.)

The past subjunctive refers to present time. It implies that the supposed case is not now a fact. (See examples 4 and 5.)

The pluperfect (or past perfect) subjunctive refers to past time. It implies that the supposed case was not a fact. (See 6 and 7.)

For details of conditional sentences, see [pp. 167–172].

281. Concession or condition may be expressed by the subjunctive without though or if, the verb preceding the subject, which is sometimes omitted.

I. Concession