-xpose- seems to object when the _varname variable contains the 
string values v1, v2, ..., vN.  For instance,
clear
set type double
set obs 10
g str1 _varname = ""
replace _varname = "v" + string(_n)
g myvar = _n
. list
     _varname      myvar
1.         v1          1
2.         v2          2
3.         v3          3
4.         v4          4
5.         v5          5
6.         v6          6
7.         v7          7
8.         v8          8
9.         v9          9
10.       v10         10
(the actual values of myvar are irrelevant, as long as myvar is a 
numerical variable)
. xpose, clear
v1 already defined
r(110);
However, v1 appears only once within _varname.  The only restriction on 
the values of _varname is that they must be 'legal' names (right?) and 
v1 is a perfectly legal name.
This situation arises since I must: 1) load data which does not 
necessarily contain names for each variable (via -insheet-); 2) 
transpose it once; 3) perform certain operations; and 4) transpose it 
again.  I cannot append a prefix or a suffix to the string values in 
_varname since some may already be at the 32-character limit for names.
Pat Joly
[email protected]
[email protected]
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/