DNA program

A DNA program (DNAプログラム), also referred as DNA data (DNAデータ) or simply DNA, is a program that makes up the physical and mental characteristics of a Reploid.

Characteristics
DNA Programs obtained from bosses and enemies can be analyzed and utilized by Zero's Learning ability, and New Generation Reploids like Axl can copy the DNA of other Reploids and take their shape and abilities. They can also be used to create power-up items for Reploids. Furthermore, by utilizing DNA Programs, the revival of deceased Reploids becomes possible, but DNA resurrection is prohibited.

History
In Mega Man X6 it is revealed that the Nightmare can change DNA and AI programs. By changing these programs, the Nightmare causes both physical and mental changes in Reploids. In Mega Man X8 it is also implicated that the Sigma Virus changes DNA programs similar to the Nightmare; Alia explained that the Copy Chip makes Reploids resistant to viruses because it changes Reploid DNA.

Trivia

 * Although not mentioned in any source, X's Variable Weapons System may use DNA program like Zero's Learning ability.