In general, each device has a "Set value", a "Readback value", and a "Digital Status". Often these come from physically different sources. In the E:HT860 example above, the "Set value" goes to a DAC in the power supply reference, while the readback comes from a monitor of the actual current going to the magnet. Not all devices have all properties. For example, there is no "Set value" on the E:HP864, the horizontal beam position after the jack pipe.
The simplest way to look at devices is the "Parameter Page", which is a generic primary application for organizing devices. The devices specific to MiniBooNE can all be found on E25, which looks like this:
Typing a device name on the left of a blank line of any parameter page, or overtyping a device name which is already there, will cause that device to read out. However, unless you save the page, the page will go back to its original configuration after you exit.
Device names are also how things are referenced in the plotting operations described throughout this document.
Another useful feature is the "Help" option. To use this, place the cursor over any device name, and hit the F7 (Help) key. This will launch a Netscape window which will give you information about that device.