updating the plan

tat_requirements/plan.md

@@ -10,7 +10,7 @@ Big questions
   controlled vocabularies need to have n sub-vocabularies. And some subclasses can probably appear with
   several super-classes. 'Periodicals' appears in around 400 subjects. It also appears that the order of sub
   and super is not well defined. In some cases 'Periodicals' is the final subject, and in other cases the
-  first subject. Curiously, topical subject bears a strong resemblence to the "tags" suggested below in [Tags](#tags).
+  first subject. Curiously, topical subject bears a strong resemblence to the "tags" suggested below in [Tags](#tag-system).
   
 ```
 INSERT INTO vocabulary (type, value) values ( 'subject', 'American literature--19th century--Periodicals' );
@@ -67,7 +67,7 @@ Code we write<a name="code-we-write"></a>
   - *maybe, discuss* change vocabulary.sql from insert to copy. It would be smaller and faster, although in reality as soon as
     it is in the database, the text file will never be touched again.
     
-- <a name="tags">tag system</a> discuss; Can/should we create a tag system to deal with ad-hoc requirements later in the project? The tags
+- <a name="tags-system">tag system</a> discuss; Can/should we create a tag system to deal with ad-hoc requirements later in the project? The tags
   are very similar to vocabulary entryies in that the tag values are controlled. The difference being a weaker
   moderation of tags and more readiness to create new tags (types). The tag table would consist of tag, value
   and is essentially a name-value system. If we create tags, should we try to enforce some data typing, that