how replace/prepend/append actually work when we edit device control rules of a policy.

[sanjay mehta 6]

that is my exact question. been trying to edit device control rules for a PC in a nested group, and then we have the option to set this to "replace' or "prepend" or "append" from previous merged policies. the description in help file is a bit confusing. can someone simplify it for me as to how it works ?

[Marcos 5,070]

The order of Device control rules determines their priority. Therefore by selecting append or pre-pend you can give rules set by a policy higher or lower priority than rules that may already exist on clients.