Production Orders

Q: We have two components ( 'X' & 'Y' ) in a production order in a process oriented production process. When 50 numbers of component 'X' are issued, we need the system to automatically issue 100 numbers of component 'Y' based on ratio of 1 to 2. Where do I specify these ratios?
A: You can define the ratio in BOM and material may be issued with reference to BOM.