I found the following information about character conversion tables..

xsm_smchar_mx.cf
This configuration file describes the SMS Center default character set.

s2aupsamplemx.cf (the user profile file)
The applied character conversion tables can be defined in each application's user profile. for example:
character table file = /etc/opt/nokia/smsc/conf/xtm_isolat_mx.cf
special character table file= /etc/opt/nokia/smsc/conf/xtm_special_mx.cf

But if the default alphabet extension table (the table which includes characters [, {, ~ and so on) is in use..
Where the extension table is defined? In the xsm_smchar_mx.cf file or in the user profile file? Or can it be defined only in user profile file?
And how it is defined? Something like
extension character table file=/etc/opt/nokia/smsc/conf/xtm_extension_mx.cf

Thanks.