https://invisible-island.net/xterm/xtoolkit/
XtAppAddConverter, XtAddConverter - register resource converter
#include <X11/Intrinsic.h>
void XtAppAddConverter(XtAppContext app_context, const char *from_type,
const char *to_type, XtConverter converter, XtConvertArgList
convert_args, Cardinal num_args);
void XtAddConverter(const char *from_type, const char *to_type, XtCon-
verter converter, XtConvertArgList convert_args, Cardinal
num_args);
app_context
Specifies the application context.
converter Specifies the type converter procedure.
convert_args
Specifies how to compute the additional arguments to the con-
verter or NULL.
from_type Specifies the source type.
num_args Specifies the number of additional arguments to the converter
or zero.
to_type Specifies the destination type.
XtAppAddConverter is equivalent in function to XtAppSetTypeConverter
with cache_type equal to XtCacheAll for old-format type converters. It
has been superseded by XtAppSetTypeConverter.
XtAddConverter is equivalent in function to XtSetTypeConverter with
cache_type equal to XtCacheAll for old-format type converters. It has
been superseded by XtSetTypeConverter.
XtConvert(3), XtStringConversionWarning(3)
X Toolkit Intrinsics – C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.1.5.2 XtAppAddConverter(3)