Access routes are used to describe relationships between files within LANSA.
When using a query tool such as LANSA/Client, access routes are very important because users do not need to understand the file structure. They only need to nominate a "base" or "starting" file and LANSA can then follow the access route chains to present the other accessible files as simple alternatives.
The relationship between records in any 2 files in any access route is predefined as "1 : 1" or "1 : many". This enables the required screen formats to be automatically designed for the type of information expected.
For example, an access path avoids the question "Given that I have a record from file A, how do I access the associated records in file B"?
File A is always the file definition that is currently being worked upon. File B can be any other physical or logical file known to LANSA.
File A can have many access routes. They could all be from file A to file B, or some could be to any other file that is related to file A.
In addition, access routes can be assigned in a chain. Thus if there is an access route from file A to file B, and an access route from file B to file C, then it is possible to start with a record from file A and locate the associated record(s) in file C.