A more thorough explanation:

A trailer clause is a promise made by an employee to give their employer the rights to any inventions they create while working for the company, and for a certain amount of time after they leave. This is also known as a holdover clause. The time limit must be reasonable for the clause to be enforceable.

For example, if a software developer creates a new program while working for a company, the trailer clause would give the company the rights to that program. Even if the developer leaves the company, the company would still own the rights to the program for a certain amount of time.

Another example would be a scientist who works for a pharmaceutical company. If they discover a new drug while working for the company, the trailer clause would give the company the rights to that drug. Even if the scientist leaves the company, the company would still own the rights to the drug for a certain amount of time.

These examples illustrate how a trailer clause can protect a company's intellectual property and ensure that they have the rights to any inventions created by their employees while working for the company.