The "--help" option of scp misses the option "d" and "f" and "t". 

1） For the option "d", the following code appears during option parsing and modifies the targetshouldbedirectory in scp.c:567 for version 9.1p1.

			targetshouldbedirectory = 1;
			break;

2) For the option "f", the following code appears during option parsing and modifies the iamremote, fflag in scp.c:570-571 for version 9.1p1.

			iamremote = 1;
			fflag = 1;
			break;

3) For the option "t", the following code appears during option parsing and modifies the iamremote, tflag in scp.c:574-575 for version 9.1p1.

			iamremote = 1;
			tflag = 1;
#ifdef HAVE_CYGWIN
			setmode(0, O_BINARY);
#endif
			break;

But they do not appear in the document provided by "--help".

Although they are both accessibility options, it may prevent users from using the relevant function.