Notification for quitting a job

Hello,

I have a question I'm trying to figure out.  I am working for a Belgian company on an open-ended contract not set for any definite period of time (this is a white collar position.)  I've been in this position for 16 months, but am currently interviewing for a job with another company.  I'm trying to determine how long the notice period needs to be before I can terminate my current contract.  My contract itself doesn't give any explicit instructions for this, it just refers to the Contracts of Employment Act of 3 July 1978. 

I tried to read through this document but the only piece of information I could find said that for white collar workers making more than 27k euros/year who had finished their probationary period and worked up to 5 years in their current post, there is a required three month notification period - but it didn't specify for whom.  Surely this must be the requirement for the company when it is dismissing the worker, rather than for the worker when they're leaving the company? 

Does anyone have any more information on this?

Thank you!