Table/Array Variable appending

[Garoun]

Been looking around the lua manuals and can't seem to find the answer to this question, more then likely I'm just blind and can't see it. Basically I was curious if/how you append more data to an already defined array/table with values present.

Some_Variable = {
[1] = {abcd},
[4] = {efgh}
};

--[[ Appending data ]]
Data_To_Append = {
[6] = {ijkl},
[3] = {mnop}
};

At the most basic level I'd like to take Data_To_Append and add it to the end of Some_Variable.

P.S. In lua are the variables of this nature considered 'Arrays' or 'Tables'?