word/kanji: the word or kanji you want to practice spelling.
furigana: a textual aid for kanji; write the kana for a kanji or romaji for kana here, if necessary.
columns: a number that defines the amount of columns for each word; how many times each word should be written.
+: add a word
-: remove a word
Custom Spelling Code: If you're familiar with JSON, you can edit the code, too. Here's a few tips:
1. The syntax for a spelling item is "{WORD/KANJI}":"{FURIGANA}", with furigana being optional.
2. If using no furigana, simply leave the string blank.
3. Please note that trailing commas will throw a syntax error, so simply delete the trailing comma and the list will be updated.