OBE is a way of designing and organizing curriculum. OBE also guides about testing and examination. Idea is to first define some learning outcomes, and then design programs and courses to meet these objectives.
Learning outcomes are first defined at program level (program learning outcomes), and then for each course further low-level outcomes are proposed (course learning outcomes). Each CLO should satisfy some PLO. A PLO may have multiple CLO's.
Evaluations (assignments, exams, etc) are also designed based on learning outcomes. Each question/problem needs to test a CLO. Normally it is required that each CLO should be tested by at least two different questions or problems.

