What is the hortative subjunctive?

It is almost the same use of the subjunctive as the jussive but is used in the first person rather than the third. It is an independent use of the subjunctive (i.e. when the subjunctive is not used in a subordinate clause). It is used to create the meaning 'let's do x' much like the jussive 'let him do x'.e.g. veniamus let's come