Maintenance Plans are software upgrade plans and can be purchased for any copy of software. While a Maintenance Plan is in effect, you can get any number of FREE upgrades to the product covered.  Upgrades are defined as changes to the major or minor version number and are enhancements to the software (i.e. switching from version 3.0 to 3.1 OR from 3.0 to 4.0).

Updates are defined as changes to the revision number and generally include small enhancements and bug fixes (i.e. switching from 3.0.122 to 3.0.134).  Updates are always FREE regardless of whether or not you have a maintenance plan.

An important rule to understand is Maintenance Plans are always contiguous. This means that a Maintenance Plan is always continued from the last day of the prior plan even if you wait to buy it.  Therefore, if you have a plan that ends on 1/1/2005 and you purchase a 6 month plan on 5/1/2005, the plan will only be good until 7/1/2005 since the 6 months is added to the last end date (1/1/2005).