Where to config "Tagcomment" in Alarm Banner

I would think this is a reserved field for legacy InTouch alarming.

This column will display the alarm comment and the tag comment data for an InTouch tag.

I don't believe it is possible to use this in Application Server alarming.

[Attribute Name].Description is the description for an attribute

[Attribute Name].DescAttrName (AlarmComment in Alarm Client Control) is used in the alarm extensions. This field will be automatically filled with me.[Attribute Name].Description. In your case, it is overridden by the constant message - "Suppress". 

Below is the list of columns supported in Alarm Client Control and TagComment is included but I am not sure if [Attribute Name].Description is mapped to it. Anyway, it is possible to use it in an alarm query like you use AlarmComment.

User1
State
Node
Group
Name
AlarmComment
Type
TimeLCT
Limit
CurrentValue
AlarmDuration
Operator
UnAckDuration
Quality
TimeLCTOAT
Value
TimeOAT
Class
Proovider
OperatorFullName
OperatorNode
OperatorDomain
TagComment
User2
User3
UTCTime
Priority

Richard is right. The TagComment field is always blank if App Server is an alarm provider. It looks like we need an enhancement.