[COA] Counting dependencies

Question

Consider the following program to be executed on this processor:
I1: Load R1, A /R1 ← Memory (A)/
I2: Add R2, R1 /R2 ← (R2) + R(1)/
I3: Add R3, R4 /R3 ← (R3) + R(4)/
I4: Mul R4, R5 /R4 ← (R4) + R(5)/
I5: Comp R6 /R6 ← (R6)/
I6: Mul R6, R7 /R3 ← (R3) + R(4)/

a. What dependencies exist in the program?

Answer 1

Data Dependencies exist in this program
e.g : in I₂ : value of operand r1 is dependent on execution of I₁ instruction 
There are no Control Dependencies in this code since there are no Transfer of Control Instructions.
Structural dependencies will depend on stages of this pipelined processor whether  they are 4 or 5 what exactly each stage does 

Comments

What does  R(1) means?

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R1 is just a register name