In the rule “Disks” just before the subrule “Executions” add the following text:

The suffix of a Disk is the last two characters of its name

In the rule “Disks” add a subrule named “Compression” and give it the following text:

If a Runner has not done so since the most recent Tick, they may spend 3 Power to perform the Compression action.

The Compression action is an atomic action in which the Runner selects two Disks in their Stack which are adjacent in list position and which may end in any suffix. The Runner combines them into one Disk by removing the names of the two Disks and replacing them with a name in the format “Disk1-Disk2.z”, where “Disk1” is the name of the first disk without the suffix and “Disk2” is the name of the second disk without the suffix. The Capacity of this disk is half of the combined original Capacity of all Disks listed in the new name, rounded down to the nearest integer but no less than 1.

When a Runner performs the Execute action, they may not Execute a Disk with the suffix “.z” unless they spend an extra 2 Power. If they do so, they may Execute each Disk listed in the name in the order listed in the name, but only pay the Power required for the Index of that “.z” Disk as well as any additional Power required by each Disk’s Effects.