Nonfinal to final 

Yes [A derived component might exist that already defines the block with a more restrictive access mode or otherwise incompatible difference. In such a case, a change would make the derived component invalid. A new nonabstract block can be added to a component type if no derived component has already defined a block that has the same name.]

Yes 

Final to nonfinal 

Yes 

Yes 

Nonabstract to abstract 

No 

Yes 

Abstract to nonabstract 

Yes 

Yes 

More restrictive access 

No 

No 

Less restrictive access 

Yes

Yes 

Add a new nonprivate block 

Yes

Yes 

Add a new private block 

Yes 

Yes 

Remove or rename a nonprivate block 

No 

No 

Remove or rename a private block 

Yes 

Yes 

Change the body of a block 

Yes [The plan run history of prior runs of this block are not updated. Therefore, they might not directly coincide with the new block contents.]

Yes 

Add, modify, or remove local block variables 

Yes

Yes 

Add, modify, or remove private block parameters 

Yes 

Yes 

Add a required parameter to a nonprivate block 

No 

No 

Add an optional parameter 

Yes 

Yes 

Remove an optional or a required parameter 

Yes [Extra arguments that are passed from the caller are ignored, making this change possible.]

Yes

Rename an optional parameter 

Yes [This change is equivalent to removing and adding an optional parameter. However, the callers might see unexpected results as the originally passed parameter value is now ignored and replaced with the default value.]

Yes

Rename a required parameter from a nonprivate block 

No 

No 

Change a parameter from being optional to being required in a nonprivate block 

No 

No 

Change a parameter from being required to being optional 

Yes 

Yes 

Change the displayMode attribute of a parameter

Yes

Yes 

Change the prompt attribute of a parameter

Yes 

Yes