scmJS docs

UNIT

The units placed on the map, 36 bytes each. Start locations are units too, of type 214.

A unit record can set the unit's hit points, shields, energy, resources and hangar as percentages or amounts, and states such as cloaked or burrowed. Each of these is used only when its bit is set in the record's fields-set or special-states word, so a record can set the hit points alone.

The units of a human player slot nobody takes are removed when the game starts; Neutral units stay. (Found playing StarCraft: Remastered.)

Name UNIT (55 4E 49 54)
Size 36 bytes per unit.
Read by The game.
Required Yes. The game does not load a map without it.
More than one copy Every copy counts: the records of all of them, in file order.
In scmJS Read, and written again when you change what it holds.

Each unit:

Offset Type Holds
0 u32 The unit's serial number, unique in the map; add-ons and nydus canals are linked by it
4 u16 X position in pixels
6 u16 Y position in pixels
8 u16 Unit type
10 u16 How the unit is linked to another (relations, below)
12 u16 Which special states the record sets (below)
14 u16 Which of the following fields the record sets (fields set, below)
16 u8 Owner, 0 for Player 1
17 u8 Hit points, per cent of the maximum
18 u8 Shields, per cent
19 u8 Energy, per cent
20 u32 Resources, for a mineral field or geyser
24 u16 Units in the hangar: interceptors or scarabs
26 u16 The special states themselves
28 u32 Unused
32 u32 Serial number of the linked unit

Relations:

Bit Meaning
0x0200 Nydus link
0x0400 Add-on

Special states:

Bit Meaning
0x01 Cloaked
0x02 Burrowed
0x04 In transit
0x08 Hallucinated
0x10 Invincible

Fields set:

Bit Meaning
0x01 Owner
0x02 Hit points
0x04 Shields
0x08 Energy
0x10 Resources
0x20 Hangar
0x40 State

Example#

A Protoss Carrier for Player 2 with half its hit points, full shields and four interceptors. The record sets the owner, hit points, shields and hangar, so the game uses those four fields and ignores energy and resources:

   0  11 00 00 00  serial number 17
   4  50 06        x 1616 px (tile 50)
   6  50 03        y 848 px (tile 26)
   8  48 00        unit type 72, Protoss Carrier
  10  00 00        not linked
  12  00 00        sets no special states
  14  27 00        sets: owner, hit points, shields, hangar
  16  01           owner: Player 2
  17  32           hit points 50%
  18  64           shields 100%
  19  00           energy 0% (not set, so not used)
  20  00 00 00 00  resources 0 (not set)
  24  04 00        4 in the hangar
  26  00 00        no special states
  28  00 00 00 00  unused
  32  00 00 00 00  no linked unit