I have tried to search for the literal values of some of the options to WinHTTP that handles SSL server certificates errors. In my case I have a development server that has a certificate with the wrong name in it, and I want to ignore the usual “The host name in the certificate is invalid or does not match” error. Since I am using LotusScript to access the COM class WinHTTP.WinHTTPRequest, I can’t simply use:

Dim http As Variant
Set http = CreateObject("WinHTTP.WinHTTPRequest.5.1")
http.Option(WinHttpRequestOption_SslErrorIgnoreFlags) = 13056

This of course generates an error, since the WinHttpRequestOption_SslErrorIgnoreFlags constant can not be found in LotusScript.
The answer couldn’t be found anywhere on MSDN, but some searching on Google led me to a page at fastbugtrack.com with some code that contains the constant I needed! So here they are for future reference:

' WinHTTPRequest options:
Const WinHttpRequestOption_UserAgentString = 0
Const WinHttpRequestOption_URL = 1
Const WinHttpRequestOption_URLCodePage = 2
Const WinHttpRequestOption_EscapePercentInURL = 3
Const WinHttpRequestOption_SslErrorIgnoreFlags = 4
Const WinHttpRequestOption_SelectCertificate = 5
Const WinHttpRequestOption_EnableRedirects = 6
Const WinHttpRequestOption_UrlEscapeDisable = 7
Const WinHttpRequestOption_UrlEscapeDisableQuery = 8
Const WinHttpRequestOption_SecureProtocols = 9
Const WinHttpRequestOption_EnableTracing = 10

The actual value for http.Option(WinHttpRequestOption_SslErrorIgnoreFlags) that I have set to 13056 (hexadecimal 0×3300) is an addition of all switches found at the WinHttpRequestOption documentation at WinHttpRequestOption_SslErrorIgnoreFlags.