This is where most of your Netrunning action takes place. Once you've jumped through the LDLs and located your target on the City Grid, your netrunner will move to the specific Subgrid where that system is to check it out.
A Subgrid Map covers about twelve square blocks, and is divided up into 10 meter squares. A system or Data Fortress (a heavily armored system) is con-structed by filling up adjacent squares of the Subgrid in a sort of loose building form. The shape of the Data Fortress on paper is only roughly like ifs real appear-ance; systems can be shaped like Corpo-rate Logos, colored polygons, Realspace buildings, abstract shapes or even person-alities (such as Disney's titanic Mickey Mouse-shaped Data Fortress in the Chiba/ Tokyo region).
When designing a Data Fortress, Referees should make some attempt to make the shape on the map roughly correspond to what the actual Netspace ICON of the fortress is, if only to make it easier on your players.
As in all Net movement, 'Runners move at a rate of five squares per turn. Movement, of course, is in straight lines, and cannot (obviously) pass through an obstacle unless you blast it to oblivion first.
Once you're down to the subgrid level, Netrunning becomes pretty simple. You try to get into the Data Fortress, either by getting through a Code Gate, or by blasting through a wall. Once inside, you move from place to place, looking for Memories to loot and other useful things. Along the way, you'll encounter various anti-intrusion programs and traps, all of which are programmed to do something nasty to you, your software, or your deck. You'll launch your own counter programs to stop them from frying something important.