Awk multidimensional Array

Shell Programming and Scripting
1

Hello Experts,,

Can anybody give me a brief idea what is following bold letter statement is for!!
what is the term called so that I can google for it..

It seems to be an array inside another array..

awk'
        /TXADDR/ { txaddr=$NF }  ##understood 
        /TXDATA/ { txdata[txaddr,++txindex[txaddr]]=$NF } ##not understood 
' infile

regards,
user_prady

2

Answered here:

http://www.unix.com/shell-programming-scripting/79306-need-logic-start-awk-sh.html\#post302231208

In short, yes, it is using the contents of one array value as an index to another array.