We can Read Protected Microcontroller PIC18F4515 Locked Software, please view the Microcontroller PIC18F4515 features for your reference:

The STATUS register, shown in Register 5-2, contains the arithmetic status of the ALU. As with any other SFR, it can be the operand for any instruction. If the STATUS register is the destination for an instruction that affects the Z, DC, C, OV or N bits, the results of the instruction are not written; instead, the STATUS register is updated according to the instruction performed.

Therefore, the result of an instruction with the STATUS register as its destination may be different than intended. As an example, CLRF STATUS will set the Z bit and leave the remaining Status bits unchanged (‘000u u1uu’) when Read Protected Microcontroller PIC18F4515 Locked Software.

It is recommended that only BCF, BSF, SWAPF, MOVFF and MOVWF instructions are used to alter the STATUS register because these instructions do not affect the Z, C, DC, OV or N bits in the STATUS register. For other instructions that do not affect Status bits. The data memory space can be addressed in several ways.

For most instructions, the addressing mode is fixed. Other instructions may use up to three modes, depending on which operands are used and whether or not the extended instruction set is enabled.

The addressing modes are:

INHERENT

LITERAL

DIRECT

INDIRECT

An additional addressing mode, Indexed Literal Offset, is available when the extended instruction set is enabled (XINST Configuration bit = 1). Its operation is discussed in greater detail in Section 5.5.1 “Indexed Addressing with Literal Offset” after Read Protected Microcontroller PIC18F4515 Locked Software.