The "T" represents "Tag" information assigned to an entry.
Prior to Dynamic Memory used by the newer scanners, the old design was the fixed Bank/Channel memory. That allowed the user to directly access a channel by keying in the channel number containing the frequency. Dynamic memory does not use channel assignments, so Uniden allows the user to assign an identification "tag" to an entry at the time of setup so that entry can be accessed directly at a later time. Use of tags is optional.
The info to the left of the decimal represents the sytem tag number and the info to the right represents the channel number. If no tags were assigned at the time of entry, then only the dashes are shown. You can always edit an entry later to assign tag information.
Here is a link to the Uniden Wiki round-about that documents how to use the tags once they are assigned.
NumberTags < UnidenMan4 < TWiki
(SNT - System Number Tag, CHNT - Channel Number Tag)
The other number you are seeing (4.13) is the current battery voltage. A fully charged battery will be somewhere in the 4.15 to 4.20 area, it seems to vary among models. As I recall, the radio shuts down around 3.49.