Well, that is not quite possible (literally at least), but there are ways of going arround the problem… WorldMachine is like an engine that only works on petrol and doesn’t store any for future uses :P. Given the amount of memory that can be involved its easy to think of why something is flushed out as soon as it isn’t needed. So there is no built-in mechanism that will help anyone regain hours of build time.
However, there is the output device! <Monty Python’s evanly chorus music> 8). For how combersome it may be to use it for this purpose, it is the only suggestion I have. This will sound more complicated than it really is, trust me ;): Connect an output device to the output port of the device output you wish to back up (save to disk) and use a file format like .ter or .r32 that will enable you to maintain great deal of the detail. This of-course can be a bit tricky to use, because if you have several things to back up in this manner, you will have to take note of what file is for what. Then, for each version you make you need to overwrite the files and mustn’t forget that… To make matter worse, each time you wish to load the terrain, you need to connect the input device to the netweork. In the end fo this message I suggest a way to do this.
There is another trick I have to tell you about. WM has a small “feature” that causes the device to loose its build content depending on the way you disconnect its output ports. :arrow: Imagine the device’s output port is connected to another device. If you click on the output port, the device will be fine, If you click on the other device’s input port, the device will loose everything and need to be built again… It was a small oversight Stephen didn’t put much enfasis on. Really not important unless BIG times are involved 
Oh well, Here is my work arround for this:
:idea: Create and arrange the 4 devices, on the bottom of the picture:
(Splitter, Switch, File Input, File Output)
Use the .r32 file format, as WM can read and write to it, and you have the most amount of detail you can write to disk.
Each time you wish to load a terrain, just go inside the switch device and check the input choice checkbox.
If at the end of your work you think everything is in OK condition, you can unhook all these devices and do a nice overnight build 
Just so you can say you didn’t load any terrain 
Update: For convenience, you may wish (or not) to check the auto-refrsh on every build or save on every build checkboxes inside the input and output devices. Avoid using the incremental file name because you would need to change the input file manually each time you build
Update 2: Unfortunately, due to a still lurking bug in version .99, I am unable to use more than one input device from different files at a time. So this can only be done once before WM v1.0 kicks in.
Cheers,
