Opcode Descriptions and Examples
PHP Manual

SUB

PHP code

<?php
/*
 * Subtracts "value2" from "value1" and stores the result into "result".
 * opcode number: 2
 */
echo 1-2;
?>

PHP opcodes

Function name: (null)

Compiled variables: none

line#op fetchextreturn operands
60 SUB   ~0 1,2
 1 ECHO     ~0
72 RETURN     1

Opcode Descriptions and Examples
PHP Manual