Thanks for your help Lynne,
Here is the solution if it can helps, first we have to declare read/write rules file in Application Definitions (Structured Tools > Structured Application Designer).
In this file we can specify what we want like this :
element "graphic" { // markup tag name is fm graphic element "Graphic"; // select all graphics framemaker elements named Graphic writer anchored frame { // if it is an anchored frame export it notation is "CGM"; // with type CGM export to file "$(docname).cgm"; // in file with the document name and extension cgm}}There is much more rules in doc that gave Lynne.
One more thing, the export didn't works for me until I fixed xml parsing errors on my dtd.
Hope it helps.