In Windows / Internet Explorer the options for different security protocols (eg: TLS 1.2, SSL 3.0, etc) are stored in HKEY_CURRENT_USER\Sofware\Microsoft\Windows\CurrentVersion\Internet Settings|SecureProtocols using a bit field. I wasn’t having much luck finding the specific values documented, only this German TechNet blog post detailing the resulting settings. So, I made my own. Here it is in C format:
/* HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings|SecureProtocols for different SSL/TLS settings. */
#define SSL_2.0 8 /* 000000001000 */
#define SSL_3.0 32 /* 000000100000 */
#define TLS_1.0 128 /* 000010000000 */
#define TLS_1.1 512 /* 001000000000 */
#define TLS_1.2 2014 /* 100000000000 */
This also applies to Internet Explorer 9, but I haven’t checked other versions.