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 characteristics of a Reploid.

Characteristics
DNA Programs obtained from bosses and enemies can be analyzed and utilized by X's Variable Weapon System, 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 Xtreme 2, the DNA Souls or Reploids are stolen by Berkana and Gareth.

In Mega Man X5, DNA programs of bosses become X's Special Weapons and Zero's techniques, and it can be used to create Power-up Parts.

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 X7, Sigma convinces Red to take Axl's copied DNA data to increase the power of the Red Alert, but by doing so Sigma also takes control over Red Alert and forces them to go after Axl, who had runaway. Sigma plans to use Axl to obtain the DNA of X. Axl can copy the appearance and abilities of enemies by taking their DNA Core.

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 New Generation Reploids resistant to viruses because it changes Reploid DNA.

Trivia

 * Although not mentioned in any source, X's Variable Weapons System may use DNA like Zero's Learning ability.
 * The Force Metal Energy from Mega Man X: Command Mission was named DNA during development.