[Fontconfig] What's the meaning of prefix dot in font family name?

[7sDream]

Hello,

I'm using the fc-list command to filter fonts by charset with the following command:

fc-list -f "%{family[0]}\n" :charset=5d0 | sort | uniq

then notice some font family name has a prefix dot(.) and wondering what this character mean.

I have done some research on the dev document and Google, but got no result.

Any information?

===== full output =====

$ fc-list -f "%{family[0]}\n" :charset=5d0 | sort | uniq
.Arial Hebrew Desk Interface
.LastResort
.Lucida Grande UI
Arial
Arial Hebrew
Arial Hebrew Scholar
Arial Unicode MS
Corsiva Hebrew
Courier New
DejaVu Sans
FreeMono
FreeSans
FreeSerif
HanaMinA
Lucida Grande
Microsoft Sans Serif
New Peninim MT
Raanana
TW-Kai
TW-Sung
Tahoma
Times New Roman

Screenshot if it helps: https://rikka.7sdre.am/files/3137d061-1e3a-4d55-8e0d-181f04bb4850.png