@winni, a.o.:
FYI
AFAIK An important difference between Default() and fillChar etc is that Default() is an
intrinsic, That means the compiler can generate less code
or sometimes no code at all! It will be resolved by the compiler at compile time and less or in some cases no code is executed by the program,
The fillchar is in effect delegated to the compiler.
So always use default() if it is available for the type. (I believe only file types are excluded)
This is documented for Delphi - hard to find, but it is - and I expect this is indeed the same in FPC and it looks like it is: compile with -al to see the difference in generated assembler. Default() generates considerably less code than FillChar.
See also wikipedia on intrinsics