[tz] question about Asia/Urumqi: why Guangdong

[Alois Treindl]

In the commentary for zone   Asia/Urumqi one reads

# Xin-zang Time ("Xinjiang-Tibet Time")
# The Gansu counties Aksay, Anxi, Dunhuang, Subei; west Qinghai;
# the Guangdong counties  Xuwen, Haikang, Suixi, Lianjiang,
# Zhanjiang, Wuchuan, Huazhou, Gaozhou, Maoming, Dianbai, and Xinyi;
# east Tibet, including Lhasa, Chamdo, Shigaise, Jimsar, Shawan and Hutubi;
# east Xinjiang, including Urumqi, Turpan, Karamay, Korla, Minfeng, Jinghe,
# Wusu, Qiemo, Xinyan, Wulanwusu, Jinghe, Yumin, Tacheng, Tuoli, Emin,
# Shihezi, Changji, Yanqi, Heshuo, Tuokexun, Tulufan, Shanshan, Hami,
# Fukang, Kuitun, Kumukuli, Miquan, Qitai, and Turfan.

Question: what is the rationale for having the Guangdong counties listed 
for this zone?

Guangdong is the province around Hongkong, with latitude around 20n and 
longitude around 115e.

This is geographically very far away from east Tibet and east Xinjiang, 
altitude around 40n and loangitude less than 82e.

What is the source for listing Guangdong here?
I presume that this is an error.