Yes, you’re correct, that was pointed out in the “PODs revisited” proposals: http://www.open-std.org/jtc1/sc22/WG21/docs/papers/2007/n2342.htm#ABI
The Embarcadero compiler docs also state it: http://docwiki.embarcadero.com/RADStudio/en/Is_standard_layout
Another key point is [class.mem]/16
Two standard-layout struct (Clause 9) types are layout-compatible if they have the same number of non-static data members and corresponding non-static data members (in declaration order) have layout-compatible types (3.9).
Note that only data members affect layout compatibility, not base classes, so these two standard layout classes are layout-compatible:
struct empty { };
struct stdlayout1 : empty { int i; };
struct stdlayout2 { int j; };