I found the list of PHP opcodes and this helped me a bit to understand the internals of PHP. But I still have problems to exactly understand the scheme used to display all informations of the opcodes on this page. For example, look here under the section PHP opcodes. I already figured out that a "!" means variable, a "->" means line of code and a "~" seems to address a "memory for internal computed results", e.g. echo 2 + 3 has to compute 2 + 3 first, so the result will be stored temporarily.
I would really appreciate a detailed explanation of the characters used in the explanations of the opcodes and the meaning of the columns "fetch" and "ext". Also, there are no opcodes for the numbers 116-131 and 137. Does this have a meaning?