XE-Series is an enhanced version of the unit that originally it was based off of. Special metal alloys are used that are kept secret from even the government (except those running tests to make sure the weapons are safe to use) A mutual agreement has been decided that the alloy remains a secret.
XE-Series Examples:
M16XE
AK47XE
F18XE
F22XE
B52XE
B17XE
B2XE
MiG35XE
AC130XE (In development)
T90XE
All of these are improved and modernized. Expensive, but very kickass.
SM-IIs (Smart Missile II) is a system that automatically detects unregistered units (aircraft, ship, tank or emplacement) and will auto-target it and guide it by GPS and lasers. Depending on its position and velocity, it will fire automatically if a computer thinks that that object is a threat. However, overrides and earlier launches must be done manually.
The SM-II Series includes:
SAM-II
AAM-II
WAM-II
ASM-II
Tomahawk-II