The new aircraft profile pages that have been rolled out last week are now linked to Type Certificates and STC's. The Type Certificate is the certification document that certifies a new aircraft design as specified in the TC.
Wikipedia puts it as follows.
"A type certificate is issued to signify the airworthiness of an aircraft manufacturing design. The certificate is issued by a regulating body, and once issued, the design cannot be changed. The certificate reflects a determination made by the regulating body that the aircraft is manufactured according to an approved design, and that the design ensures compliance with airworthiness requirements. The regulating body compares design documents and processes to determine if the design meets requirements established for the type of equipment." From http://en.wikipedia.org/wiki/Type_certificate.
The website feels that adding the Type Certificate links to corresponding aircraft will help users compare the websites posted data with what is contained in the TC and add a wealth of additional information for those interested in a particular aircraft make.
Due to the nature of the Type Certificate if an operator or any other person would like to operate an aircraft outside its certified constraints then they must obtain a Supplemental Type Certificate. This STC goes through a process of certification to ensure that the design change does not negatively impact safety. At the same time, if a modification of a component will change operating characteristics or limitations on an aircraft, those new standards are now connected through the STC to that aircraft if the modification is made.
Wikipedia defines it is as, "A supplemental type certificate (STC) is an FAA approved major modification or repair to an existing type certified aircraft, engine or propeller. As it adds to the existing type certificate, it is deemed 'supplemental'." From http://en.wikipedia.org/wiki/Supplemental_type_certificate.
The STC section of the aircraft pages allows users at a quick to what kind of modifications have been approved for a particular type certificate. For some aircraft there may be "hundreds" of approved STC's.