Hello everyone ! I am currently reading a paper about crystal properties of R2CuIn3 where R=Tb,H0, Er. It states : 1.that based on bibliography they are crystallized in the hexagonal system P6/mmc. With the use of POWLS software , it was found that there was a second phase Cu2In , so its intensities where subtracted. 2.There are two intensities reversed in (114) and (212) meaning that I114 >>I212. 3. The reversing of these intensities was accomplished by describing an equivalent hexagonal system (194) with (a=b,2c) , where Tb,Ho,Er is at (0,0,0.25) and CU,IN is at (1/3,2/3,z) My question is about 2 and 3 ? What does it mean that the intensities where reversed and that to eliminate this an equivalent system was proposed with Cu,In at (1/3,2/3,z) . (Who's z? Z is dead :) ) But really what is z for and how can a hexagonal system be equivalent by changing z? Please help me I am really confused about this subject - new with crystallography Thank you in advance !