What URL extensions are available?

Hi guys, I'm creating a simple angularJS project to grab some info from my characters weekly progress. All is going well in terms of fetching data thanks to the help pages and online searches I did. There's just one thing I can hardly find any info about and that's the additional parameters at the end of an api get. The ones added behind the & character. Is there a list somewhere on what is what? Example: &definitions=true gives you an explanation of the data you requested &mode=<number> filters the result (just found this https://gist.github.com/jdstein1/76efaf11e664133f3ca8 ) But there are more that might improve my efficiency I presume. For instance on the site above I also see: lc=en, I assume the language of the result fmt=true and lcin=true, got no clue what they do. Is there a list or something about these? Many thanks!