Our doc team is astonishingly good.... They even got you covered on this one....
Check out (on your local hard drive or download from our website), doc #724, the Opto Control Manual.
Page 405 (App C-1). It shows all the files and their types.
Here is the guts of it;
<strategy>.cdb OptoControl strategy database
<strategy>.cdb.txt Text file containing basic strategy information, such as tags and their data types.
<strategy>.crn Run file (compiled file that is sent to the controller)
<strategy>.crn1 Intermediate run file (component of the run file)
<strategy>.crn2 Intermediate run file (component of the run file)
<strategy>.crn3 Intermediate run file (component of the run file)
<strategy>.inc Initialization data for variables with “Init on Download” option (component of the run file)
<strategy>.inf Strategy configuration information
<strategy>.$cdb Temporary OptoControl strategy database file
<strategy>.lcdb OptoControl strategy database lock file
<strategy>.per Persistent variable definitions
<strategy>.<controller>.cdf Controller download file for special circumstances
<chart name>.cht Chart
<chart name>.ccd Compiled chart code (component of the run file)
<chart name>.con Online compiled chart code
<filename>.wth Watch window file (you name the file)
<filename>.otg Exported I/O configuration file (you name the file)
<strategy.date.time>.zip Strategy archive file
As you can see from that list, the answer to your question is the .ccd is the complied chart.