# HG changeset patch
# User Adam Chlipala <adam@chlipala.net>
# Date 1328275856 18000
# Node ID be1ed46d73e2012d6be948b953fd305bcb79bc65
# Parent  ac141fbb313a1a797339ffeaf521d5f4e380e21f
Mention convention for parens in selected expressions

diff -r ac141fbb313a -r be1ed46d73e2 doc/manual.tex
--- a/doc/manual.tex	Thu Feb 02 11:40:10 2012 -0500
+++ b/doc/manual.tex	Fri Feb 03 08:30:56 2012 -0500
@@ -2178,7 +2178,7 @@
 
 Additionally, an SQL expression may be inserted into normal Ur code with the syntax $(\mt{SQL} \; E)$ or $(\mt{WHERE} \; E)$.  Similar shorthands exist for other nonterminals, with the prefix $\mt{FROM}$ for $\mt{FROM}$ items and $\mt{SELECT1}$ for pre-queries.
 
-Unnamed expression columns in $\mt{SELECT}$ clauses are assigned consecutive natural numbers, starting with 1.
+Unnamed expression columns in $\mt{SELECT}$ clauses are assigned consecutive natural numbers, starting with 1.  Any expression in a $p$ position that is enclosed in parentheses is treated as an expression column, rather than a column pulled directly out of a table, even if it is only a field projection.  (This distinction affects the record type used to describe query results.)
 
 \subsubsection{DML}