rewrote if-thrn-else

bash_prog_ref.md

@@ -285,22 +285,23 @@ Loop control: `break [n]`, `continue [n]`
 Conditionals
 ------------
 
-### `if - then - else`
-
-```bash
-if cmd1; then
-   list1; # iff cmd1 succeeds
-elif cmd2; then
-   list1; # iff cmd1 fails but cmd2 succeeds
-else 
-   alt;   # otherwise
-fi
-```
-
-`cmd?` may be _any_ commands (often `(())` or `[[]]`); `list?` and `alt`
-are lists.
-
-There are $\geq 0$  `elif` clauses, and $\leq 1$ `else` clause.
+### _if - then - else_
+
+| `if` _`test-list1`_`;` `then` 
+|   _`consequent-list1`_`;` 
+| `elif` _`test-list2`_`;` `then`
+|    _`consequent-list2`_`;` 
+| `else` 
+|    _`alt-list`_`;`
+| `fi`
+
+_`consequent-list`_ _n_ is executed iff _`test-list`_ _n_ succeeds; _`alt-list`_
+is executed if none of the _`test-list`_s succeeds. \
+_`test-list?`_ is often a `(())` or `[[]]` conditional but may be _any_ lists,
+including a simple command. 
+
+The `else` and `elif` clauses are optional, there may be more than one `elif`
+clause.
 
 ### `case - in`