Country codes (thanks to Dominic Sinyakov)
 
AFG Afghanistan
AHO Netherlands Antilles
ALB Albania
ALG Algeria
AND Andorra
ANG Angola
ANT Antigua-Barbuda
ARG Argentina
ARM Armenia
ARU Aruba
ASA American Samoa
AUS Australia
AUT Austria
AZE Azerbaijan
BAH Bahamas
BAN Bangladesh
BAR Barbados
BDI Burundi
BEL Belgium
BEN Benin
BER Bermuda
BHU Bhutan
BIH Bosnia and Herzegovina
BIZ Belize
BLR Belarus
BOL Bolivia
BOT Botswana
BRA Brazil
BRN Bahrain
BRU Brunei Darussalam
BUL Bulgaria
BUR Burkina Faso
CAF Central African Republic
CAM Cambodia
CAN Canada
CAY Cayman Islands
CGO Congo
CHA Chad
CHI Chile
CHN China
CIV Côte d'Ivoire
CMR Cameroon
COD Democratic Republic of the Congo
COK Cook Islands
COL Colombia
COM Comoros
CPV Cape Verde
CRC Costa Rica
CRO Croatia
CUB Cuba
CYP Cyprus
CZE Czech Republic
DEN Denmark
DJI Djibouti
DMA Dominica
DOM Dominican Republic
ECA Organization of Eastern Caribbean States (OECS) (Davis Cup Entity)
ECU Ecuador
EGY Egypt
ERI Eritrea
ESA El Salvador
ESP Spain
EST Estonia
ETH Ethiopia
FIJ Fiji
FIN Finland
FRA France
FSM Federated States of Micronesia
GAB Gabon
GAM Gambia
GBR Great Britain
GBS Guinea-Bissau
GEO Georgia
GEQ Equatorial Guinea
GER Germany
GHA Ghana
GRE Greece
GRN Grenada
GUA Guatemala
GUI Guinea
GUM Guam
GUY Guyana
HAI Haiti
HKG Hong Kong
HON Honduras
HUN Hungary
INA Indonesia
IND India
IRI Iran
IRL Ireland
IRQ Iraq
ISL Iceland
ISR Israel
ISV Virgin Islands
ITA Italy
IVB British Virgin Islands
JAM Jamaica
JOR Jordan
JPN Japan
KAZ Kazakhstan
KEN Kenya
KGZ Kyrgyzstan
KIR Kiribati
KOR Korea
KSA Saudi Arabia
KUW Kuwait
LAO Laos
LAT Latvia
LBA Libya
LBR Liberia
LCA Saint Lucia
LES Lesotho
LIB Lebanon
LIE Liechtenstein
LTU Lithuania
LUX Luxembourg
MAC Macau
MAD Madagascar
MAR Morocco
MAS Malaysia
MAW Malawi
MDA Moldova
MDV Maldives
MEX Mexico
MGL Mongolia
MKD Macedonia
MLI Mali
MLT Malta
MNT Montserrat
MON Monaco
MOZ Mozambique
MRI Mauritius
MSH Marshall Islands
MTN Mauritania
MTQ Martinique
MYA Myanmar
NAM Namibia
NCA Nicaragua
NED Netherlands
NEP Nepal
NGR Nigeria
NIG Niger
NOR Norway
NRU Nauru
NZL New Zealand
OMA Oman
PAK Pakistan
PAN Panama
PAR Paraguay
PER Peru
PHI Philippines
PLE Palestine
PLW Palau
PNG Papua New Guinea
POC Pacific Oceania (Davis Cup Entity)
POL Poland
POR Portugal
PRK North Korea
PUR Puerto Rico
QAT Qatar
ROU Romania
RSA South Africa
RUS Russia
RWA Rwanda
SAM Samoa
SEN Senegal
SRB Serbia
SEY Seychelles
SIN Singapore
SKN Saint Kitts and Nevis
SLE Sierra Leone
SLO Slovenia
SMR San Marino
SOL Solomon Islands
SOM Somalia
SRI Sri Lanka
STP Sao Tome and Principe
SUD Sudan
SUI Switzerland
SUR Surinam
SVK Slovakia
SWE Sweden
SWZ Swaziland
SYR Syria
TAH Tahiti
TAN Tanzania
TGA Tonga
THA Thailand
TJK Tajikistan
TKM Turkmenistan
TKS Turks and Caicos Islands
TLS Timor-Leste
TOG Togo
TPE Chinese Taipei
TRI Trinidad-Tobago
TUN Tunisia
TUR Turkey
TUV Tuvalu
UAE United Arab Emirates
UGA Uganda
UKR Ukraine
URU Uruguay
USA United States
UZB Uzbekistan
VAN Vanuatu
VEN Venezuela
VIE Vietnam
VIN Saint Vincent and the Grenadines
YEM Yemen
YUG Yugoslavia (former)
ZAI Zaire
ZAM Zambia
ZIM Zimbabwe