Type 1: Dropped numeral "1".
Type 2: Top and side panels with special background.
Type 3: Space between "L"  of  "UNIVERSAL" and "R" of "SALVADOR" very wide.
Type 4: Left top panel with special background.
Type 5: Raised "V" in "CENTAVOS".

ONLY RECORDED PANE KNOWN TO EXIST


1883 SAN SALVADOR to BARRANQUILLA, COLUMBIA
    Type 2 of 10c x 2 with 1c and 5c issues for 26c proper single outbound registered rate
tied with negative star cancels alongside December 22 cds.

Via Panama. Struck with black pre-philatelic oval cancel with manuscript
"Received from the British Agency on January 2nd."

ONLY KNOWN PANAMA PRE-PHILATELIC CANCEL USED
ON EL SALVADOR MAIL DURING THE PHILATELIC PERIOD


1879 SAN SALVADOR to NEW YORK
10c (Type 1) for single outbound rate to North America, posted June 27.


1882 LA LIBERTAD to BORDEAUX, FRANCE *
10c (Type 5) and 1c with "PARA" maritime cancels alongside August 8 cds.
Endorsed "CITY OF PANAMA". Backstamped Bordeaux, September 6.


NATAL SPECIMENS
Stamps provided to the Natal Central Post Office by the UPU.
Affixed to album pages and handstamped with purple "SPECIMEN",
typed used between 1902 - 1903.


1885 STA ANA to PARIS, FRANCE*
10c x 2 (Types 4 and 5) with 1c and 5c issues for proper 25c single outbound registered rate.
Postmarked July 10. Received Paris, August 14.


1886 SAN SALVADOR to AHUACHAPAN *
10c Diagonal bisect to produce 5c single interior rate tied with December 7 cds.

ONE OF ONLY TWO RECORDED 10c BISECTS ON COVER


1883 ACAJUTLA to PARIS, FRANCE
10c x 6 (in order, Types 4, 5, 2, 3, 5, 4) with 1c and 5c issues on wrapper,
proper 66c multiple outbound rate via Panama, all tied with
purple negative star cancels alongside July 6 cds.

LARGEST RECORDED USAGE OF 10c ISSUE

* Certified by organizations recognized by the FIP.