 when software is derived from two or more sources having incompatible viral licenses in which the derivative work could not be re-licensed at all.Although the concept is generally associated with licenses that promote free content, some have attempted to compare it to the proprietary original equipment manufacturer source code software distribution agreements which grant licensees the right to redistribute copies of the software, but restrict what terms can be in the end user license agreement.Such licenses could be considered viral if they led derivative or connected software to gain the same license.