Paho MQTT library names – Stack Overflow

I found list of paho MQTT libraries installed in Linux:

libpaho-mqtt3a.so -> libpaho-mqtt3a.so.1
libpaho-mqtt3a.so.1 -> libpaho-mqtt3a.so.1.3
libpaho-mqtt3a.so.1.3
libpaho-mqtt3as.so -> libpaho-mqtt3as.so.1
libpaho-mqtt3as.so.1 -> libpaho-mqtt3as.so.1.3
libpaho-mqtt3as.so.1.3
libpaho-mqtt3c.so -> libpaho-mqtt3c.so.1
libpaho-mqtt3c.so.1 -> libpaho-mqtt3c.so.1.3
libpaho-mqtt3c.so.1.3
libpaho-mqtt3cs.so -> libpaho-mqtt3cs.so.1
libpaho-mqtt3cs.so.1 -> libpaho-mqtt3cs.so.1.3
libpaho-mqtt3cs.so.1.3

I understand that file names with ending with as means asynchronous. But what about a, c, cs?

What they are used for