[citation needed] Before preparing a procedure, it may be appropriate to carry out a risk assessment, estimating how likely it is for an emergency event to occur and if it does, how serious or damaging the consequences would be.
For the same reason, a revision numbering system and a schedule of amendments are frequently used with procedures to reduce the potential for errors and misunderstandings.
[5] The document itself may be just a few lines, perhaps using bullet points, flow charts or it may be a detailed set of instructions and diagrams, dependent on the complexity of the situation and the capabilities of those responsible for implementing the procedure during the emergency.
The act of producing the procedures may also highlight failings in current arrangements that if corrected, could reduce the risk levels.
There are many well documented examples of this such as: Three Mile Island accident, the Chernobyl disaster and the Deepwater Horizon drilling platform explosion in April 2010.