| SYNOPSIS | 
#include <dkim.h>
DKIM_STAT dkim_add_xtag(
	DKIM *dkim,
        const char *tag,
        const char *value);
);
Requests that the named tag and value be added to the signature header
field when it gets generated by
dkim_getsighdr(). | 
|---|
| DESCRIPTION | 
| Called When | dkim_add_xtag() can be called at any time prior to calling
dkim_eom(). |  | 
|---|
| ARGUMENTS | 
    | Argument | Description | 
|---|
 | dkim | Message-specific signing handle, returned by
        dkim_sign(). |  | tag | A pointer to a null-terminated string that specifies the
	tag name to be added to the signature.  This must not be a tag
	that is already supported by the library, as those are generated
	automatically.  It must also meet the syntax rules of RFC6376
	Section 3.2. |  | value | A pointer to a null-terminated string that specifies the
	tag value to be added to the signature.  It must meet the syntax
	rules of RFC6376 Section 3.2. |  | 
|---|
| RETURN VALUES | 
DKIM_STAT_OK -- success
DKIM_STAT_INVALID -- dkim referred to a verifying header rather
    than a signing header, or one of the provided values contained a syntax
    error, or the tag named is one already supported by the library, or
    the named tag has already been added to the signature
DKIM_STAT_NORESOURCE -- out of memory
DKIM_STAT_NOTIMPLEMENT -- feature is not implemented for this installation
 | 
| NOTES | 
It is legal to include whitespace in values according to RFC6376 Section
    3.2.  However, this will interefere with the automatic wrapping and
    formatting of the signature performed by the library.  A mechanism to
    indicate valid line break points will be included in a future release.
 |