What does "pchMessage" mean ?

[cudjex]

Hey

I'm trying to understand some things about coins.

When I look to Saturncoin's main.cpp, pchMessage value is :a

Code:

unsigned char pchMessageStart[4] = { 0xfa, 0xb4, 0xad, 0xcb }; 

In Litecoin's main.cpp :

Code:

unsigned char pchMessageStart[4] = { 0xfb, 0xc0, 0xb6, 0xdb };

In Dogecoin :

Code:

unsigned char pchMessageStart[4] = { 0xc0, 0xc0, 0xc0, 0xc0 };

So what is this and how it works ?