I'll try to be brief, my problem involves interpreting data sheets of components. For example on the data sheet for a SCR I see the following data:

Min / Typical / Max
Gate Trigger Voltage (Continuous dc) : 0.4 0.6 0.8

Now, does that mean I require voltage within those ranges- or can I use the full value of the anode / cathode? For example if it also has a "Peak Repetitive Off−State Voltage" of 600 volt(dc)- can the gate handle that?

due to process variations in the manufacturing process, there will be a range of values for the gate trigger voltage. Basically what that is telling you is to make sure your gate voltage is no less than 0.8V to insure that the SCR will trigger. Statistically, though, most of the triggering will occur at 0.6V for a majority of the SCRs they produce.