Of course there are rules. This is FIFA you're talking about, there are always rules.
Simple enough, FIFA states that the playing equipment, which comprises
of a jersey or shirt with sleeves, shorts, socks, shinguards, and
footwear, may consist of no more than four colors. Adhering to the
same rule, as well, the goalkeeper must clearly distinguishable from
the players on both teams. Before competition, teams must inform FIFA
of two kits: one predominantly colored and one predominantly white.
One of those kits are designated the official kit, while the other is
defined as the reserve in case of clash between teams. Likewise, the
goalkeeper will provide three different colored kits to wear
throughout the competition, as the possibility for clashing is
greater.
The numbers and letters used on the uniform to identify players are
subject to far more complex rules, as they must fit within a certain
template. Numbers on the back of the shirt must be centered and
between 25 cm and 35 cm in height, as well as between 3 cm to 5 cm in
thickness, while the numbers on the front of the shirt and shorts must
be between 10 cm and 15 cm in height. Numbers can be applied to either
leg of the shorts.
Unfortunately for companies such as Nike, which prides itself on
iridescent or chrome numbers, equipment may not be made of reflective
material or change color or appearance due to lighting or water and
must be distinguishable from the rest of the kit. If a number were to
clash with the rest of the uniform, a squared number zone would be
created on the front and back of the shirt.
Another form of identification, the player's name, follows a similar
rule in that it must be in contrasting color to the shirt. The
player's name, which must be positioned at least 4 cm above the number
on the back of the shirt, must be between 5 cm and 7.5 cm.
In addition, both the names and numbers appearing on the shirts or
shorts must be permanently sewn or ironed directly onto the uniform,
and no player with temporary means, such as Velcro, will be allowed in
the competition.
Uniforms are allowed a decorative element, such as sublimated stars
and stripes on a United States kit, but only if it does not dominate
the shirt or shorts and/or limit the ability of a player. As long as
the decorative element does not give the impression of a
manufacturer's identification, a religious or criminally affiliated
symbol, or any registered trademarks, FIFA will sign off on the
design.
Another guideline the kit must follow is that each sleeve, no matter
the length, must keep a 12 cm by 8 cm free zone for FIFA specific
badges. This is where the World Cup logo will be placed.
On the front of the shirt, the country can place an identification no
more than once, whether it is the official member association emblem,
mascot, flag, name, or nickname. The identification must be positioned
at chest level and must not interfere with the legibility of the
number. The national flag may be placed on the sleeve opposite of the
free zone or on the back collar of the shirt.
The identification may also be placed at the bottom of each number on
the back of the shirt.
Likewise, the shorts can use an identification (flag, emblem, etc) no
more than once and be place only on the front. In addition to the
rule, a flag can be placed on the front waistband of the shorts.
Member identification must be on the opposite side of any
manufacturing logos and numbers and vary in measurements, depending on
the form of identification.
Socks must display the same two forms of member identification, to be
chosen among the member flag, emblem, or name.
The reigning champion of the FIFA World Cup must display a champions
badge throughout the tournament. In 2014, Spain must wear a specially
made badge on the front of the shirt at chest level. The badge
measures 80 mm by 55 mm and will be provided by FIFA.
In continuing the theme of past champions, member associations that
have won one or more editions of the World Cup may display a
five-pointed star(s) on the shirt and/or shorts. The star(s) must be
positioned immediately above the member identification.
FIFA will also provide two captain's armbands for international play,
composed of the colors of the country's flag, but contrasting to the
uniform. Free of any manufacturer identification, sponosors, or
decorative element, the armband will simply have the word "captain"
and FIFA logo.
The goalkeeper may wear gloves of any color, but must be in contrast
to the shirt. The goalkeeper's name or number may appear once on the
left-handed glove, while the country's flag or emblem may appear once
on the right.
At their discretion, the goalkeeper may also wear a cap of any color,
to be affixed with no more than one form of identification, as well as
their name. The same goes for any headbands or arm/wristbands that a
player may wear.
Like member identification logos, manufacturer logos are also subject
to regulations. The manufacturer may place its name/wordmark and logo
on any equipment item it so chooses, but are only permitted to use it
three times throughout the kit. It should be noted that both socks
count as one item and shoes are at the player's discretion. The
manufacturer logo can be placed in any of the following locations: the
bottom of the sleeves, the chest opposite of the member identification
logo, the shorts adjacent to the number, and/or the socks.
In some cases, such as Adidas' three stripes, a manufacture logo may
be incorporated into a strip, which may be placed along the player's
side, the cuffs of the sleeve or shorts, and/or the top of the socks.
In some instances, a manufacturer may choose to form a repeated
pattern of logos to make such a strip.
Furthermore, it's not just the players whose look is subject to FIFA's
strict rules. Coaches, referees, ball boys, and even the game-used
ball must use specific logo placement. If any participating member of
the country does not follow these rules, they are subject to a penalty
and can be docked points or banned from future tournaments. In a World
Cup qualifier ten years ago, Cameroon wore Puma's one-piece uniform,
resulting in penalties and FIFA amending regulations to outlaw such
designs in the future. To avoid such situations moving forward, FIFA
now requires manufacturers to submit all designs one year in advance.