| LEADTOOLS DICOM C DLL Help > Quick Reference > Data Types > Keywords Used in Declarations | 
LEADTOOLS uses the following keywords in declarations of functions, structures, and datatypes:
| Keyword | Definition and Usage | 
| EXT_CALLBACK | Defined as _cdecl ; used as an attribute for all toolkit callback functions. | 
| pEXT_CALLBACK | Defined as EXT_CALLBACK *; used as an attribute when defining pointers to toolkit callback functions. |