What is an MSpec
 

I have come across this term several times. For example, in an FAA Advisory Circular I am reading it says, "The flightcrew should not apply this 15 percent safety margin to the landing distance determined for compliance with any other OpSpec/MSpec requirement."

I know the M is for management but what is this?

Op Spec refers to the codified requirements of operating an air carrier (Part 135/121) and includes defining equipment, aircraft, procedures, training, and airports served. M Spec refers to Part 91 aircraft operations.

3-736 DISCUSSION. This section and sections 4, 5, and 6 of Volume 3, Chapter 18, discuss each standard template available for issuance by the automated Operations Safety System (OPSS), also known as the Web‑based Operations Safety System (WebOPSS). These templates are more commonly referred to as “paragraphs.” The standard paragraphs discussed in this order are limited to operations in accordance with Title 14 of the Code of Federal Regulations (14 CFR) parts 91, 91 subpart K (91K), 121, 125 (including Letter of Deviation Authority (LODA) holders (125M)), 135, and 145.

A. Definition of OpSpecs. The standard paragraphs for parts 121, 125, 135, and 145 are called operations specifications (OpSpecs).

B. Definition of MSpecs. The standard paragraphs for part 91K are called management specifications (MSpecs).

C. Definition of LOAs. The standard paragraph for part 91 and 125M are called letters of authorization (LOA).

FAA documentation