XVaCreateNestedList - allocate a nested variable argument list
typedef void * XVaNestedList;
XVaNestedList XVaCreateNestedList(int dummy, ...);
  - dummy
- Specifies an unused argument (required by ANSI C).
- ...
- Specifies the variable length argument list.
The XVaCreateNestedList function allocates memory and copies its
  arguments into a single list pointer, which may be used as a value for
  arguments requiring a list value. Any entries are copied as specified. Data
  passed by reference is not copied; the caller must ensure data remains valid
  for the lifetime of the nested list. The list should be freed using
  XFree when it is no longer needed.
Xlib - C Language X Interface