Many applications that create metafiles prepend a 22-byte 'Placeable File Header' to the metafile: https://msdn.microsoft.com/en-us/library/windows/desktop/ms534075(v=vs.85).aspx
Magic number 0x9AC6CDD7, 2-byte handle, always 0, skip 16 bytes, File type (1 or 2), header size in words, always 9.
Byte sequences
Position type
Absolute from BOF
Offset
0
Byte order
Value
D7CDC69A0000{16}01000900
Name
Windows Metafile Image without Placeable File Header
Description
File type (1 or 2), header size in words, always 9. Version either 01 or 03