  Let R be a subring of Q and recall from math.LO/9910161 that an R-module G is
a splitter if Ext_R(G,G)=0. We correct the statement of Main Theorem 1.5 in
math.LO/9910161. Assuming CH any aleph_1$-free splitter of cardinality aleph_1
is free over its nucleus as shown in math.LO/9910161. Generally these modules
are very close to being free as explained below. This change follows from
math.LO/9910161 and is due to an incomplete proof (noticed thanks to Paul
Eklof) in the first section of math.LO/9910161. Assuming the negation of CH, in
Shelah [Sh:F417] (work in progress) it will be shown that under Martin's axiom
these splitters are free indeed. However there are models of set theory having
non-free aleph_1-free splitter of cardinality aleph_1.
