When you create monitors or rules to check logfiles you might want to include both the logfile directory and logfile name in the alert description. You can do that with the following parameters

For monitor:
Logfile Directory : $Data/Context/LogFileDirectory$
Logfile name: $Data/Context/LogFileName$
String: $Data/Context/Params/Param[1]$

For rule:
Logfile Directory : $Data/EventData/DataItem/LogFileDirectory$
Logfile name: $Data/EventData/DataItem/LogFileName$
String:  $Data/EventData/DataItem/Params/Param[1]$

Kevin Holman, a premier field engineer at Microsoft, has a great list of parameters at his blog, here.