How to use \processifversion in Latex

Question

I am using the \processifversion{tag} to create various versions of report. I have two questions on how to use this command or its equivalent \begin{tag} ... \end{tag}:

In a table, I wanted to pick up a specific line for a "tag" using "\processifversion{tag}{a & b & c \\\hline}", but got error message "Missing } inserted". How to have \processifversion work together with table (tabular environment)?

I intended to use \processifversion{tag1, tag2}{TEXT} to include "TEXT" when tag1 or tag2 is included. However, I found with this, "TEXT" is always included even tag1 and tag2 are both excluded. How to fix this?

I added the following simple sample. This code works. However, if I want to output "Hello PDF world!" by turn on either "PDF1" and "PDF2", what is the most efficient way to do it?

The real case I am working is more complicated: 1. I need to output 8 different versions, where some versions may have common part; 2. the common part could be very lengthy. So it may not be reasonable to repeat the common part for each tag.

\documentclass[a4paper,11pt]{article}
\author{Al Alexander}
\title{}
\usepackage{versions}
\includeversion{PDF}
\excludeversion{HTML}
\begin{document}
\maketitle
\tableofcontents
% if "PDF" has been included, do this:
\processifversion{PDF}{Hello PDF world!}
% if "HTML" has been included, do this:
\processifversion{HTML}{Hello HTML world!}
\end{document}