Unit Commands

All UNITs can execute the COMMANDs listed in Table . To execute a command, the player selects one or more UNITs and directs them to apply the command, optionally with a target CELL, UNIT, or BUILDING. The UI MUST provide a reasonably convenient way to do this selection and assignment. For example, the UI might allow the player to select a single CELL and then provide a checkbox-list of UNITs occupying that CELL. The player would then select a set of UNITs by picking from the checkboxes. The UI would offer a list of possible COMMAND (via buttons or a pick-list) and the player would pick a COMMAND. That COMMAND would apply to all selected UNITs. If the COMMAND requires a target, the UI would prompt the player to pick a target CELL, BUILDING, or UNIT. Finally, when the UI has all the information about the COMMAND, it would schedule execution of the COMMAND. Other, less clumsy, interaction mechanisms are possible; the exact mechanism is up to the designers.

Table: Commands available to UNITs.

Command	Recur	Length	Target	Description
Produce	yes	Tbl	occupied CELL	Produce one FRU of the RESOURCE for the occupied CELL's TERRAIN TYPE
Move	yes	Sec	adjacent CELL	UNIT moves into the adjacent CELL
Build	no	Tbl	bldg. type	Construct a building of the specified type on the occupied CELL
Attack	yes	base move	UNIT or BUILDING	Attack and destroy a UNIT or BUILDING in an adjacent CELL
Defend	yes	instant	none	Stand and defend; take no other action and do not move.
Invade	yes	base move	BUILDING	Invade and occupy a BUILDING in an adjacent CELL without destroying it

The properties of a COMMAND are:

Recur

Whether this COMMAND recurs automatically or not. If ``yes'', then as soon as the UNIT completes this COMMAND, it automatically re-executes the command and schedules a new event for it. This process continues until the player assigns the UNIT a new COMMAND or the UNIT is destroyed. If ``no'', then the UNIT becomes idle at the end of the COMMAND and takes no other action until the player explicitly directs it to.

Length

How long it takes to execute this COMMAND, measured in ticks of the GLOBAL CLOCK.

Target

What other thing this COMMAND affects, if any. Many times, the target will have to be explicitly specified by the player, but some times it can be inferred automatically. For example, the Produce COMMAND can only apply to the CELL that the UNIT is occupying.

Description

What the COMMAND does.

Note: The UI MUST NOT allow the player to select an illegal action. The following are illegal:

1. It is illegal for a player's UNITs to Attack or Invade his or her own UNITs or BUILDINGs.
2. It is illegal for a UNIT to Attack or Invade a CELL not immediately adjacent to the UNIT. The UNIT MUST Move up to adjacent to the CELL in question and then invoke the Attack command.

OPTIONAL RULE The designers MAY extend the Attack and Invade commands to support ``Move-then-attack'' semantics.