Understanding the purpose of each of the eight sections of a material data safety sheet (MSDS) will help you quickly and efficiently get the information you need about whatever chemicals you're using. The first section is "Identity," and it provides the various names the chemical is known by (including street names and trade names). It also provides the contact information for the manufacturer of this chemical.
Chemical Abstract Services is a company that distills down all of the information on a given chemical into an abstract and then assigns that chemical a CAS number. This number is often helpful to emergency response personnel. If an EMT asks you for this number, you simply have to look in this part of the MSDS. The emergency phone number for this chemical is in this section also. If you call it, the operator will probably ask you for the CAS number.