The VM provides per class access flags such as ACC_SYNTHETIC for use by reflection APIs. The JVMS describes access flags and the class file format version(s) for which they are defined.

Is it expected that the flags provided to reflection are only those appropriate for the class file format version?
In one case, for a class file with version 49, 0x1000 access flag is present though it is not defined as ACC_SYNTHETIC until class file format version 50.