I found a program which uses a dll-file, which starts with MZx in the DOS header. I never saw this before in my life. I get ZERO results at google when i try to find explanations what this means. Here is a screenshot:

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What exactly does the MZx mean? Are there differences to a typical MZ header? Can i replace the dll with a "normal" one which starts with MZ or will it be not compatible?

CodePudding user response：

Only the first two bytes are part of the signature, the rest is the configuration of the DOS program:

typedef struct _IMAGE_DOS_HEADER
{
     WORD e_magic; // MZ
     WORD e_cblp;  // Bytes on last page of file
     WORD e_cp;    // Pages in file
     ...

These "unusual" values are either required by the DOS program (unlikely in a .dll) or used as some kind of marker/storage for something. Either way, leave the values alone...