Update README.md

README.md

@@ -12,7 +12,15 @@ The cumulative dataset is under an apache 2.0 license, but the sources differ on
 
 I am unfamiliar with licenses in general, so if someone sees any issues with the licensing situation, please let me know.
 
-## Dataset Sources
+
+# Metadata meaning:
+source: self-explanatory
+
+### specific to manual fanfic:
+missed_lines: number of lines in the document where the index matched between the unaligned source and translation, but the content of the lines did not meet the match threshold. This number being high relative to the number of lines in the document indicates either a poor translation, or some other factor causing the source and translation to differ beyond the norm.
+inserted_lines_src: lines that only appear in the source document, and matches are found surrounding them, indicating the line is some kind of insertion (like a note, afterword, title, etc). Is generally safe to ignore unless it's significant compared to the number of correctly aligned sentences, which would indicate a poor matchup between source and translation sources, for one reason or another.
+inserted_lines_src: same as above, but for the target document instead
+# Dataset Sources
 news_commentary (unknown license?)
 
 iwslt2017 (cc-by-nc-nd-4.0)