An apparatus and method for utilizing any arbitrary mixture ratio of multiple fuel gases having differing combustion characteristics, such as natural gas and hydrogen gas, within an internal combustion engine. As mentioned above, such inconsistencies occur when two or more sets of lock information, relating to the same resource, convey inconsistent information about locks requested andor granted on that resource. Thus, the increase of volume for the pack is reduced as much as possible. First user input selects one of the type nodes in the schema for a view. When the two version indicators are not identical, the system raises an exception.