Integer constants in PIC assembly: decimal vs. hex

I am doing programming in PIC based micro controller (microchip). The PIC model that I used is PIC16.

I have issue on classifying the data type

e.g. MOVLW xxxx where xxxx are the following:-

• 0x23: hexadecimal

• 23: decimal

• D'20': hexadecimal

• 1Bh: hexadecimal

• b'00101100': binary

Why are 1Bh, D'20', 0x23 hexadecimal? Is there any other way to show hexadecimal in PIC assembly