Can any one tell joins between eAM and Project accounting modules

Hi Team,

Can any help on joins between eAM modules and project accounting modules

      PA.PA_PERIODS_ALL PAP,
PA.PA_PROJECT_TYPES_ALL PRJT,
PA.PA_EXPENDITURE_BATCHES_ALL EXPB,
PA.PA_EXPENDITURES_ALL EXP,
PA.PA_COST_DISTRIBUTION_LINES_ALL CDIST,
PA.PA_EXPENDITURE_ITEMS_ALL EXPI,
PA.PA_TASKS TASK,
PA.PA_PROJECTS_ALL PROJ

WIP.WIP_DISCRETE_JOBS DJOB        ------ this table we have join for  both projects and work orders but  PROJECT_ID and TASK_ID columns  having null values entire table  both the columns .
WIP.WIP_ENTITIES WORD ------  work order
WIP.WIP_OPERATIONS OPRN          ----- work order task