Here is a link to an article that talks about Capable to Promise. The article is on the website capa-software-solutions.com. Take a look at the article I believe it will help you understand the basics of CTP.

Capable to Promise (CTP) considers availability of both materials and capacity, giving a very realistic picture of whether demand can be satisfied within a given time fence. To avoid “over promising” and “under promising” on job orders you have to set your delivery dates based on available capacity and material constraints. Most respectable capable to promise systems are integrated within some type of manufacture scheduling system. The scheduling system will contain information about the production cycle times and the schedule.

Scheduling solutions carry large amounts of information about production times and machine loading times. Looking in these programs is the best place to ask for capacity capability. Most systems integrate the functionality into a “what if” scenario, allowing the scheduler to add dates to the system and test delivery dates and efficiency without releasing a schedule to the production floor. This software allows the user to define and implement many different problem solving methods, ensuring all problems (supplier, customer, product, etc.) can be managed as required by the user.

Additional solutions that are available provide an interface that allows the sales team to enter products and their quantity. The system will then report when it is possible to deliver a job and the impact that may be on other related jobs and possibly raw materials.

Cambridge Journals
In line with the commitment of Cambridge University Press to advance learning, knowledge and research worldwide, the Press currently publishes over 220 peer-reviewed academic journals for the global market.

Manufacturing.gov
The Manufacturing.gov website is dedicated to providing the most comprehensive, and current information on issues surrounding the competitiveness of American manufacturers.