5.16  BASE   The BASE action builds a naval base in any coastal area you own at a cost of 10 treasury BPs. You must specify one adjacent sea space as the entrance of the base (ships can come and go only through this sea area). The new base can't be used until the following turn.
Format [ "BASE" ] [ WHERE ] [ ENTRANCE ] [ BLANK ]

5.17  CLOSE   The CLOSE action is used to close a naval base that you own. There is no cost in BPs. Any ships in the base when you close it are added to your naval reserve (this applies the same whether they're laid up or in commission). After a CLOSE action you can't recover ships from your reserve until the following turn. You can't re-open a closed base, but you can build a new one in the same place.
Format [ "CLOSE" ] [ WHERE ] [ BLANK ] [ BLANK ]

5.18  DISOWN   The DISOWN action is used to disown an area and all the armies in it. Both the area and everything in it become neutral (sometimes done in order to cut supply costs, or to build neutral buffer states). There is no cost in BPs.
Format [ "DISOWN" ] [ WHERE ] [ BLANK ] [ BLANK ]

5.19  AIR   The AIR action is used in World Empires to increase the strength of your air force. The cost is 7 BPs per strength. If you don't give a number of strengths to build then the number will be all that you can afford. There's no "all but" format.
Format [ "AIR" ] [ BLANK ] [ BLANK ] [ NUMBER OF LEVELS ]   increasing your air force
This action is not used in Medieval Empires and European Empires.