xpath question - Mailing list pgsql-novice

Just a quick question, not being a big xpath or xml user in the past.

Why does this:

select xpath('//Abstract/AbstractText[1]',content) from medlinexml;

return an array for each entry rather than a single xml entry?  I
thought that appending the [1] should not return an array, but a
single xml value instead.

Thanks,
Sean

example output below

 {"<Abstract>
 <AbstractText>Strains of Pseudomonas aeruginosa, isolated from the
sputum of relatively fit patients with cystic fibrosis (CF) who had
been recently colonized by the organism, showed typical cultural and
serologic characteristics. The majority of strains of P. aeruginosa
isolated from CF patients with chronic bronchopulmonary infection had
3 distinctive features, loss of 0 serotype reaction, expression of a
new somatic antigen, and sensitivity to normal human serum. Patients
with organisms with one or two of these features were more severely
affected by the disease. The appearance of these variants may
represent a critical stage in the progression of CF.</AbstractText>
 </Abstract>"}
 {"<Abstract>
 <AbstractText>The changes in airway caliber and plasma cyclic-AMP
levels after intravenously administered aminophylline, and the effect
of DL- and D-propranolol on these responses have been investigated in
a double-blind manner in normal subjects. Aminophylline 5.6 mg/kg was
given intravenously over a 10-min period and the airway response was
measured as change in specific airway conductance (delta SGaw) in the
body plethysmograph. In the initial study in 6 subjects, orally
administered placebo or propranolol was followed 2 h later by
intravenously administered aminophylline. Neither placebo nor
propranolol alone caused any change in SGaw at 2 h. After placebo,
intravenously injected aminophylline produced a 30% increase in SGaw,
reaching a peak 5 min after injection. This response was equivalent to
77% of the maximal response to 400 micrograms inhaled albuterol in the
same subjects. After propranolol, the airway response to aminophylline
was attenuated, with a 53% reduction in delta SGaw at the time of peak
response. In a further study on 6 subjects, intravenously given
aminophylline produced a 25% increase in SGaw and a 51% increase in
plasma cyclic-AMP levels after placebo tablets. Pretreatment with 40
and 80 mg DL-propranolol caused a dose-dependent reduction of both the
airway and plasma cyclic-AMP response to aminophylline. The airway
response to aminophylline was not attenuated by D-propranolol so the
effect of DL-propranolol is thought to be due to beta-adrenoceptor
blockade. The absence of any detectable change in SGaw after
DL-propranolol suggests there is little resting sympathetic tone to
the airways in normal subjects. In the absence of sympathetic
stimulation, the rapid response to aminophylline is unlikely to be due
to phosphodiesterase inhibition. The attenuation of the airway and
cyclic-AMP response by propranolol suggests that part of the action of
aminophylline may be due to beta-agonist activity.</AbstractText>
 </Abstract>"}