cdm really usefull?

[collinm]

hi

there are the cdm, ldm and pdm for data modelling

conceptual data modelling
logicic data modelling
physical data modelling


some software allow to generate theses three types of models, some other not

i don't see the utility of cdm

when i check this web page

Conceptual, Logical, and Physical Data Models

if find useless the cdm

why create a cdm when we use crow's foot, baker, ie... notation

i found usefull cdm for the merise method... but it's only used in france...

does somebody create cdm and ldm?

why?


thanks

[collinm]

web page is http://www.1keydata.com/datawarehous...ng-levels.html