Parameters are used to pass value from one function to another.
You can add or change parameters in Designer or Programmer menu.
Lets go step by step. So far you have a file with access paths on it. If you type F against a file you will see all functions built on that file
Following image shows all the functions built on your file.
Take option P to add parameters to a function as shown in above image and folloiwng screen will open.
There are following 3 ways to pass parameters.
1. FLD - Provide the field name of the parameter of the function.
2. RCD - Provide the file name and then choose which field of the file will be used as a parameter.
3. KEY - Provide the file name and keys of the file will be passed as parameter.
Please see an example below.
Now we have Roles and Usage for Parameters. For our example we passed parameters as KEY but i only want to use Horse code as a parameter. Here usage and role helps.
Types of Usage.
1. I - Input. Parameter will be passed as input.
2. O - Output. Parameter will be used as output means this "Display racing results" function will return value in this parameter.
3. B - Both. Parameter will used to pass value and return value both.
4. N - Neither. Parameter will not be used.
5. D - Drop. Parameter is dropped and can not be used.
Types of Role.
1. R - Restricted. Function will read access path to find exact matching record.
2. M - Map. Function will read access path from the beginning.
3. P - Position. Function will read access path to find closedst matching record.