Field 43 is as @bbozo described traditionally Card Acceptor name and location though with a general standard format and is sometime referred to interchangably with REG-E address; but it is not.
It is also not a TLV field as there are no tags defined in ISO-8583 (any version) for it. A 3rd party entity could stray from ISO specification and define it as TLV, but if they do you need to clarify if it is text TLV, BER-TLV, or another TLV variant.
Returning to the usage of DE43 the usage varies greatly, but depending on the specific ISO-8583 flavor it has different formatting.
The standard one is generally:
Position 1-23 Address or Merchant Name
Position 24-36 City
Position 37-38 State/Region (ISO-3166 Alpha 2)
Position 39-40 Country (ISO-3166 Alpha 2)
That said I looking at recently about 200 million unique transactions and found about 260k unique values of the field for a particular client after ignoring things like ticket number or customer IDs that sometimes come in the field such as something like VRZN 999-999-9999.
VISA & MasterCard each have slight variants of the first two sub-fields as well by a single character length. Some regional switch formats also format it differently.
Prime variants I see are for P2P/OCT transfer and for Airline tickets; both of which contain specific details of the purchase similar to a wireless bill, but with a very specific format. Those contain specific captialized letters like "XFER", "VISA TRANSFER", and a couple other variants.
I see the state code all over the field and the only thing relatively consistent is the country code.
Lastly some regional networks put the merchant name in DE048 and put the physical address in DE043 and so you won't get all of the info in just DE043 but have to look at both to get the merchant name. VISA & MasterCard do not use DE048 though for that purpose.