Syntax: choose from drop down list
For Refresh
-type walks, this is the minimum time period to try
refreshing a URL. The actual refresh period is dynamically computed
for each URL based on how often it changes, and will not be less than
this value. This prevents too much time being spent refreshing a very
dynamic page (i.e. constantly refreshing it and loading the web
server). Typically set to 1 minute.