To say that a Power of Attorney ("POA") is "durable" means that the powers given in the instrument stay in effect even if the principal becomes incapacitated and unable to manage his or her own affairs. When a POA in Florida is not durable, the powers cease if the principal becomes incapacitated--thereby requiring that a court-ordered guardianship be established. Most estate planning attorneys would advise to avoid guardianship if possible.
Under Florida law, to make a POA durable, it must contain the following or similar language: "This durable power of attorney is not terminated by subsequent incapacity of the principal except as provided in chapter 709, Florida Statutes." The words used must that show that it is the principal's intent that the authority conferred is exercisable notwithstanding the principal's subsequent incapacity.
So why make a POA durable? The answer should be obvious: the need for a POA often does not even arise until the principal is incapacitated and unable to act for them-self. Having a POA which is not durable might be useful in a very limited situation. For example, if a person intends to be out of town and wishes to appoint another person to act for them under very limited circumstances, then the POA might be acceptable if not durable. Otherwise, it would seem that the ultimate purpose of the POA is undermined if it ceases when the principal is incapacitated.