Basically, anything you find inside [] are said to be parameters that can be filled in at the time of deployment. If deploying through the GUI, you will have a chance to fill in this data for your devices. For example, say you have the following in your template:
+ hostname [hostname]
+ snmp-server community [community] RO
+ tacacs-server key [tacacs_key]
Then in the deployment window, you will have a chance to fill in these values. See the online help at http://server/help/rme/fundamentals/config_DeplyBaslinTempUI.html
for more information on deploying baselines.