in carboxylic acid: Hydroxy and keto acids. ...not the same. The 2-hydroxy acids form cyclic dimeric esters (formed by the esterification of two molecules of the acid) called lactides, whereas the 3- and 4-hydroxy acids undergo intramolecular esterification to give cyclic esters called lactones.
VBA's ActiveWorkbook property refers to the workbook with the focus. The active workbook may or may not contain the code that's referencing the active workbook, which is an important distinction. It's perfectly acceptable to use this property to reference the active workbook from code inside the active workbook.
Personal Workbook is a specially reserved named file which is generated (first time around) automatically to store the recorded macros. The name given to this file (which is still treated like any other Excel file) is Personal.xls/xlsm/xlsb.