An ICALTODO - iCal To Do File is a storage and data type file that is used by the Spotlight program on Mac OSX systems. The Spotlight program is a program used for searching in OSX. The actual ICALTODO fille is created in the iCal program and contains the data entered onto the iCal to reference dates and times that are important for you to remember.
These file types are saved to the iCal directory and can be found by following the directory path of the current user into the Library/Caches/Metadata/iCal folder.
To edit an iCal file you will need to place it in the proper directory, mentioned in the previous paragraph. Once the file has been placed you can access the file by opening the iCal program and select the file from the list shown to the left. Once the program has opened the ICALTODO file remove the "new event" message from the date where you would like place your reminder, if you also need a reminder for where the event will take place you can put that information into the "location" area and finally change the hour:minute:am/pm boxes to reflect the time you need to arrive.
Additionally, if you need this same reminder repeated select how often using the "repeat" button, if you desire you can attach documents to the reminder and even invite people to attend with the "invitees" link to select people from your email address book.
A useful program to help keep track of where you need to be, when to be there, any documents you might need and even who you have invited.