Format Specifier In C++

Hello All, I'm posting this question after searching Google, but didn't quite understand. In the following code

CString str1;
str1.Format(_T("%%02d°%%02d'%%1.%dlf\""), val)
//val is an integer

This displays decimal degrees, minutes and seconds. But in the seconds part why is it 1.%dlf, why is the decimal, long n float used and also from my understanding %% means print the percentage but the % symbol is not displayed in my interface.