1 - "Generate data" is function of 2nd Pass.
Pass 2 (assemble instructions and generate object program) :
1. Assemble instructions (generate opcode and look up addresses)
2. Generate data values defined by BYTE, WORD
3. Perform processing of assembler directives not done during Pass 1
4. Write the object program and the assembly listing
http://solomon.ipv6.club.tw/Course/SP.941/sp2-1.pdf