The same word may occur more than once in the paragraph, but you want them to have different second level entries. In that case, you have to scroll through the document and insert those entries manually. A concordance file contains the words you want to mark as index entries, together with the words by which they are referenced in the index. By creating a concordance file, you can index all the words in a document at the same time. You can also use the same concordance file to index multiple documents, saving time and creating consistent indexing across documents.
Word inserts a table with two columns and two rows.
In the first column, type a word that you want Word to look for in your document. The words in the first column are the words that will be marked as index entries. Capitalization must match exactly. In the second column, type the word by which you want your entry in the first column to be indexed. In most cases, the two are the same.