Notices for military duty must be given as follows.
1. When given. Members of the state military forces must receive reasonable prior notice of active state service appropriate to the duty to be performed.
2. How given. Notices may be given orally or in writing. Orders conspicuously posted during a regular meeting of the unit, not less than 4 days prior to the date fixed in the order, are sufficient.
3. Dates fixed by law. When drill dates have been fixed by law, orders or regulations, no further notice is required.