AT+KTCPSND= <session_id>, <ndata>, what does ndata do?

as I send TXSTRING("–EOF–Pattern–"); at the end,
so what does ndata really do?
Can I just set it for max possible like 1024 all the time?

commands that are really not care is bad design.
I tried to use KTCPSTART instead but seems very unreliable, letters showing up one byte a second.