In 1987 Fender started the production of Squier guitars in Korea, at first in the Samick, Young Chang and Sung-Eum factories.
The serial number of the guitars released in the '80s by the Samick factory featured a “S” prefix.  The first figure of the following 6 or 7-digit number usually indicated the year of production. 
The Young Chang and Sung-Eum factories adopted a serial number composed by an “E” prefix plus a 6 or 7-digit number.  In the '80s, the first number was related to the period of the issue as follows: in 1987 and 1988 they used as first number “1”, in 1989 “2”.  Since 1990 they started to use a clearer serialization scheme, and the first number after the “E” prefix indicated the solar year.  Thus, “E0” prefix was used in 1990, “E1” and “E2” were used again, respectively in 1991 and 1992!  Fortunately, it was possible to distinguish them because the serial numbers “E1” and “E2” of the '80s were very light silver, while those of the '90s were black.
In addition, it must be considered that sometimes the serial number of the Korean guitars consisted only of numbers, without letters, and that some rare Stratocasters from Young Chang in the first years of production exhibited the serial number “E7” or “E9”!  Actually, a great confusion! 

1989 Squier headstock with black "S" serial number (Courtesty of miurasv from photobucket)

'80s Korean Squier headstock with "E" light serial number (Courtesy of Reverb)

In 1990 Fender started to manufacture Squier guitars in Cor-Tek (Cort) and Saehan (Sunghan) factories and the prefix of the serial numbers were changed respectively in “CN” and “VN”, in which “N” means ‘90s.  The first figure of a following 6-digit number provided the year(s) of the issue.  For example: NK4xxxxx = 1994-1995.
In 1997 a serial number composed by “KC” or “KV” prefix plus 8-digit number was used.  The first two figures provided the year(s) of production.   For example: KV97xxxxxx = 1997-1998.

"VN2" Squier Strat headstock

"CN4" Squier Strat headstock

In 1995 the serial number of the "standard" Squier Stratocasters moved to the neck plate

"M" AND "J" SERIES

In 1991 and 1992, few Korean Squier Stratocasters featured a serial number composed respectively by a “M1” (or “J1”) and “M2” prefixes.

1991 "M1" Series Squier II heastock

1992 "M2" Series Squier II heastock

SQUIER II

The serial number of the Korean Squier II guitars was placed on the headstock and started with “E” or “S” according to the production’s factory.
The Indian Squier II guitars followed an American-like serialization scheme (“E” for '80s and “N” for '90s).  The serial number was on a sticker on the back of the neck, just above the neck plate.  Today many Squier II Stratocasters made in India lacked this sticker because it easily came off.

Decals on a Korean Squier II Stratocaster, "E" serial number (reverb)

Decals on a Korean Squier II Stratocaster, "S" serial number

Indian Squier II Stratocaster headstock (Reverb)

2000s KOREAN SPECIAL EDITONS

A few Special Edition Fender guitars, like the Lite Ash Stratocaster or the Koa Stratocaster, were manufactured in Korea by Cort.  An all numerals 8-digit serial number based on the year/month/production run number of the guitar (YYMMXXXX) was used.
For example, serial number 04032203 would have been made in March 2004 with the production number 2203.

VINTAGE MODIFIED SERIES

In 2007 some Squiers were again manufactured in India, including those of the Vintage Modified Series (whose serial began with SH).
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Other Indian serial numbers:
2007-08   CS07, SH07, ZSSH07 + 6 digits
2008-09   SH08, NSHJ08, ZSSH08 + 6 digits
2009-10  NSHI09, NSHJ09, NSHA09, NSHK09, NSHD09, NSHE09, NSHF09, NHSG09, NSHH09 + 6 digits
2010-11   NHS10 + 6 digits
2011-12   NHS11 + 5 digits