CC1125: cc1125 preamble

Hi,

I configure two node with diffrent preamble Size(one node preamble length : 1 Byte and Other is 4 Byte), But still communication is OK, Why,

How strict it.

data = 0x35;
    HalRfWriteReg(PREAMBLE_CFG0, &data, 1);

    data = num << 2 | word; // num =2 and 6  and word= 0xcc
    HalRfWriteReg(PREAMBLE_CFG1, &data, 1);