
https://secondlifestorage.com/t-LG-LGDB218650-Cell-Specifications
John Robinson Pierce (March 27, 1910 – April 2, 2002), was an American engineer and author. He worked extensively in the fields of radio communication, microwave technology, computer music, psychoacoustics, and science fiction.[1] As a sideline to his professional career he wrote science fiction for many years under various names: John Pierce, John R. Pierce, and J. J. Coupling. Born in Des Moines, Iowa, he earned his PhD from Caltech, and died in Palo Alto, California from complications of Parkinson’s Disease.
Using ${} is a way to create dynamic variables, simple example: ${‘a’ . ‘b’} = ‘hello there’; echo $ab; // hello there
Source: Using braces with dynamic variable names in PHP – Stack Overflow
