select clause not according to SQL standard

hi all!

i am using version 7.4.7/Debian of postgres.

as far as i understand the standard, the following situation should not
be possible. neither is it stated in the manual that the select is not
conforming to the standard.

i have the following data:

table L:
LNR ORT LCODE MENGE
L1 Graz A 1000
L2 Wien C 500
L3 Wien C 1500
L4 Linz B 1000
L5 Graz B 300

table P:
PNR PNAME ORT PREIS
P1 Alpha Wien 50.00
P2 Delta Linz 95.00
P3 Sigma Linz 75.00
P4 Omega Wien 40.00

now the problem:

select l.ort;
gives:

ORT
Graz
Wien
Wien
Linz
Graz

select l.ort from p;
gives:

ORT
Graz
Wien
Wien
Linz
Graz
Graz
Wien
Wien
Linz
Graz
Graz
Wien
Wien
Linz
Graz
Graz
Wien
Wien
Linz
Graz

i know what it is doing, but still i feel this should be considered a
bug as this "feature" is very inviting to bugs in scripts. i asked
around and everybody seems very astounished by the results one gets here
from postgres.
please let me know if i am mistaken
i thank you 1000000 times for your excellent work! -> i am trying to
replace oracle with postgres at our university and the more
standard-compliant postgresql is, the better are my chances :-)

regs,
klaus