It is imperative for reserve soldiers to avail themselves when such a slot opens up. This is especially true when soldiers reach the maximum grade for their MOS within a unit. Further progression depends upon acquiring the MOS of the higher grades within the present unit or transferring to another unit where promotion within the present MOS is still possible. Certain key positions, mostly SFC and higher, require the soldier to have a secret clearance. Terrain analysts at all grades must have such a clearance as well as sergeants first class progressing to master sergeant.
Clearances are expensive to process and can take a long time.
Soldiers considering a career in the reserve component can speed this up by making sure the interviewers receive all requested background information as early and as completely as possible.