The ER diagram details the database structure currently implemented for the current milestone. The ER diagram is simplified as compared to the original plants below in the platform design as the database is used locally for a single user on browser.

The database is implemented on indexedDB (noSQL). An external open-source library, alasql, which is able to mimic SQL structure is used. However, direct interaction is used on indexedDB when alasql failed to implement certain features.

The ER diagram details the database structure that we are planning to implement for platform, if time permits.

We will be implementing the database with SQL, Heroku and SQLite3.

	Details
Description	The user table stores the details of the users which includes user ID, username and email. These attributes must be unique to each user.
PrimaryKey	User ID. This is generated in our backend to uniquely identify a user.

	Details
Description	The Organization will be interacting with the folders and file manager.
PrimaryKey	Organization ID + User ID
Extra Note	An organization can have multiple parents and multiple children to allow a more flexible way in setting permission controls. However, a cycle whereby an organization may become a parent or grandparent or ... ancestor of itself. The solution for this use case will be handled by the back-end to prevent this.

	Details
Description	A session is a timed event that an organization can create for a single file.
PrimaryKey	Session ID

|Extra Note|The session password can act as a first line of authorization for the audience like in the use case of a lecture session or a project meeting.|

	Details
Description	To group the files
PrimaryKey	Folder ID + Organization ID

|Extra Note|The folder main role is to store permission data for our software engineers to identify permission. Similar to folders in Windows, the folder are unique individuals who can only have at most 1 parent folder.

Similar to the organization, it is possible for a folder to be an ancestor of itself. The solution will be handled by the back-end of the software to prevent this.|

	Details
Description	To handle files that the organizations (users) have created.
PrimaryKey	Organization ID + File ID

|Extra Note|The file manager main role is to store permission data for our software engineers to identify who has the permission to access the file.|

	Details
Description	Store images
PrimaryKey	Image ID

	Details
Description	To store text by paragraphs.
PrimaryKey	File ID + Text ID
Extra Note	The implementation will not be discussed in the ER diagram but the paragraphs order will be stored in another entity and each paragraph will be tied to some annotations.

	Details
Description	To store the order of the paragraph texts
PrimaryKey	File ID + Order Number + Paragraph Number
Extra Note	The paragraph order is useful to act as a pointer to keep the annotations in-line.

	Details
Description	To categorize the annotations.
PrimaryKey	Annotation ID
Extra Note	The annotations will be pinned to the paragraph to ensure it will not be messed up when the user sorts its notes.

	Details
Description	To store the annotation files
PrimaryKey	Annotation Number