What does 16u and 128u mean? The below is a snippet of a code for operating SI4455 Rf module with Arduino. I have some doubts which I'd like to seek some help in clearing.

byte numOfBytes = *pSetPropCmd++;

    if (numOfBytes &gt; 16u) // What does this 16u mean?
    {
        /* Initial configuration of Si4x55 */
        if (SI4455_CMD_ID_WRITE_TX_FIFO == *pSetPropCmd) 
        {
            if (numOfBytes &gt; 128u) // What does this 128u mean?
            {
                /* Number of command bytes exceeds maximal allowable length */
                return SI4455_COMMAND_ERROR;
            }

            /* Load array to the device */
            pSetPropCmd++;
            WriteEZConfigArray(numOfBytes - 1, pSetPropCmd);

            /* Point to the next command */
            pSetPropCmd += numOfBytes - 1;

            /* Continue command interpreter */
            continue;
        }


In the above snippet, what does 16u and 128u mean?. I think its meaning u for unsigned, but still not clear as what does 16u and 128u mean. 

Rgds
VD
It means that it is a unsigned value. Because the compiler checks for signed and unsigned in the same operation this is used (amongst others) to avoid warnings.

This is explained on stackoverflow here https://stackoverflow.com/questions/14844119/define-foo-1u-2u-4u-what-does-1u-and-2u-mean