Key notes are when you have tags with a code pointing to something on a drawing, and a schedule or legend that puts a description against each code.
For example town planning drawings may have codes that describe the intended facade system.
Revit has Keynoting functionality but it can be complex to manage. A simpler way is to use a Symbol (General Annotation) tag and a Note Block schedule.
With this method the code and note are contained within the annotation tag, not model elements (which is what keynoting does).
An alternative to Note Block schedules is to use a Legends instead.
You still place tags and give them a code, but you write the description as text in a legend instead of into the tag.
The advantage of Note Blocks is that the schedule will capture all tags as they are created. With Legends you need to manually check how many codes there are and make sure all are included.
The disadvantage of Note Blocks is formatting is limited, and entering data and editing it later can be difficult if the text runs over more than one line.
PLACE TAG
From Annotation tab, select Symbol, from Properties window select the type.
Select the Number of Leaders you want from the options bar.
Then place it in the view you want to tag (e.g. an elevation).
To add an arrow select the tag and hit Leader: Add
Select the tag, and look at the Properties window.
You will see parameters for Code, Note etc. Type the information in you require against the relevant parameter.
OR
Select the tag, click on the question mark, type in the code.
Add the rest of the information in the schedule.
CREATE NOTE BLOCK SCHEDULE
From View tab, Schedules, select Note Block.
Select the family name of the tag you used, then give the schedule a name.
Select the fields to include, filter, sort, format as required.
Make sure you UNTICK Itemize every instance under the Sorting/Grouping tab.
PLACE NOTE BLOCK SCHEDULE ON SHEETS
To place the note block schedule on to sheets open the sheets and drag and drop the schedule.
TIPS
If you want the same tag multiple times just copy the tag. Use Copyclip and Paste between different views.
Because the information is contained in the tag itself:
deleting tags deletes the information
changing the family of the tag deletes all information (changing type is OK).
The arrow used is a type parameter. To change the arrow:
Select a tag of the type you want to change
Edit Type
Select a different arrow type from the Leader Arrow Head parameter.