Quote from: deepceleron on April 14, 2016, 05:31:30 PM

There are many script instructions that are simply math or stack manipulation that were written for versatility or future use. To eliminate potential bugs and undefined states, some non-money transfer instructions as originally implemented by Satoshi have been disabled. Transactions including them would be invalid, and modified or non-Satoshi clients including them in a block would result in an invalid "fork" block, ignored by the rest of the network.

You can see which instructions are disabled: https://en.bitcoin.it/wiki/Script#Splice

Well, it makes sense ^^ I've notice that some instructions was disable and I asked myself why, now I have the answer, security purpose ^^
But does that imply that we can play with every other instructions and assume It will be verify and accepted by a miner (with the appropriate fee ofc) ?