Only started a few days ago but most seems to be done. However, I am still struggling with the first row describing the expedition. The preamble says "letters in the first row must be replaced....". Is this ALL letters or just some? If just some - how many?
Are the replacements real letters or morse code? How does this affect the down answers? I really do not understand the reference to code options (six each) or 'blanks'.
A significant shove in the right direction would be greatly appreciated. Many thanks.