In the
 United States Court of Appeals
                For the Seventh Circuit
                          ____________

No. 02-1486
CLOUD CORPORATION,
                                                   Plaintiff-Appellant,
                                  v.

HASBRO, INC.,
                                                  Defendant-Appellee.
                          ____________
             Appeal from the United States District Court
        for the Northern District of Illinois, Eastern Division.
             No. 97 C 3457—Rebecca R. Pallmeyer, Judge.
                          ____________
   ARGUED NOVEMBER 8, 2002—DECIDED DECEMBER 26, 2002
                          ____________


  Before POSNER, ROVNER, and WILLIAMS, Circuit Judges.
   POSNER, Circuit Judge. “Wonder World Aquarium” is a
toy that Hasbro, Inc., the well-known designer and mar-
keter of toys, sold for a brief period in the mid-1990s. The
toy comes as a package that contains (we simplify slightly)
the aquarium itself, some plastic fish, and, depending
on the size of the aquarium (for this varies), large or
small packets of a powder that when dissolved in dis-
tilled water forms a transparent gelatinous filling for the
aquarium. The gel simulates water, and the plastic fish
can be inserted into it with tweezers to create the illusion
of a real fish tank with living, though curiously inert, fish.
2                                                No. 02-1486

“Pretend blood,” included in some of the packages, can be
added for even greater verisimilitude. The consumer can
choose among versions of Wonder World Aquarium that
range from “My Pretty Mermaid” to “Piranha Attack”—the
latter a scenario in which the pretend blood is doubtless a
mandatory rather than optional ingredient.
  Hasbro contracted out the manufacture of this remark-
able product. Southern Clay Products Company was to
sell and ship Laponite HB, a patented synthetic clay, to
Cloud Corporation, which was to mix the Laponite with
a preservative according to a formula supplied by Hasbro,
pack the mixture in the packets that we mentioned, and
ship them to affiliates of Hasbro in East Asia. The affiliates
would prepare and package the final product—that is,
the aquarium, the packet of gel, and the plastic fish
(and “pretend blood”)—and ship it back to Hasbro in
the United States for distribution to retailers.
  The project was in operation by the middle of 1995.
Hasbro would from time to time issue purchase orders
for a specified number of large and small packets to
Cloud, which would in turn order the quantity of Laponite
from Southern Clay Products that it needed in order to
manufacture the specified number of packets. The re-
quired quantity of Laponite depended not only on the
number of large and small packets ordered by Hasbro
but also on the formula that Hasbro supplied to Cloud
specifying the proportion of Laponite in each packet. The
formula was changed frequently. The less Laponite per
packet specified in the formula, the more packets could
be manufactured for a given quantity of the ingredient.
  Early in 1997 Hasbro discovered that its East Asian
affiliates, the assemblers of the final package, had more
than enough powder on hand to supply Hasbro’s needs,
No. 02-1486                                                3

which were diminishing, no doubt because Wonder World
Aquarium was losing market appeal. Mistakenly believing
that Hasbro’s market was expanding rather than contract-
ing, Cloud had manufactured a great many packets of
powder in advance of receiving formal purchase orders
for them from Hasbro. Hasbro refused to accept delivery
of these packets or to pay for them. Contending that this
refusal was a breach of contract, Cloud sued Hasbro in fed-
eral district court in Chicago, basing jurisdiction on diver-
sity of citizenship and seeking more than $600,000 in dam-
ages based mainly on the price of the packets that it had
manufactured and not delivered to Hasbro and now was
stuck with—for the packets, being usable only in Wonder
World Aquaria, had no resale value. After a bench trial,
the district judge ruled in favor of Hasbro.
    Cloud does not quarrel with the district judge’s findings
of fact, but only with her legal conclusions. The governing
law is the Uniform Commercial Code as interpreted in
Illinois.
  The original understanding between Hasbro and Cloud
regarding Cloud’s role in the Wonder World Aquarium
project either was not a contract or was not broken—
probably the former, as the parties had not agreed on the
price, quantity, delivery dates, or composition of the
packets. These essential terms were set forth in the pur-
chase orders that Hasbro sent Cloud, confirming discus-
sions between employees of Cloud and Kathy Esposito,
Hasbro’s employee in charge of purchasing inputs for the
company’s foreign affiliates. Upon receipt of a purchase
order, Cloud would send Hasbro an order acknowledg-
ment and would order from Southern Clay Products the
quantity of Laponite required to fill the purchase order.
  In October 1995, which is to say a few months after the
launch of Wonder World Aquarium, Hasbro sent a letter
4                                               No. 02-1486

to all its suppliers, including Cloud, that contained a
“terms and conditions” form to govern future purchase
orders. One of the terms was that a supplier could not
deviate from a purchase order without Hasbro’s written
consent. As requested, Cloud signed the form and re-
turned it to Hasbro. Nevertheless, to make assurance
doubly sure, every time Hasbro sent a purchase order to
Cloud it would include an acknowledgment form for
Cloud to sign that contained the same terms and condi-
tions that were in the October letter. Cloud did not sign any
of these acknowledgment forms. The order acknowledg-
ments that it sent Hasbro in response to Hasbro’s pur-
chase orders contained on the back of each acknowledg-
ment Cloud’s own set of terms and conditions—and the
provision in Hasbro’s letter and forms requiring Hasbro’s
written consent to any modification of the purchase or-
der was not among them. There was a space for Hasbro
to sign Cloud’s acknowledgment form but it never did
so. Neither party complained about the other’s failure
to sign the tendered forms.
   Hasbro placed its last purchase orders with Cloud in
February and April 1996. The orders for February spec-
ified 2.3 million small packets and 3.2 million large
ones. For April the numbers were 1.5 and 1.4 million.
Hasbro notified Cloud of the formula that it was to use
in making the packets and Cloud ordered Laponite from
Southern Clay Products accordingly.
  Now as it happened Southern Clay Products was hav-
ing trouble delivering the Laponite in time to enable
Cloud to meet its own delivery schedule. In June 1996,
amidst complaints from Hasbro’s East Asian affiliates
that they were running out of powder, and concerned
about the lag in Laponite deliveries, Hasbro notified Cloud
that it was to use a new formula in manufacturing the
powder, a formula that required so much less Laponite
No. 02-1486                                                 5

that the same quantity would enable Cloud to produce
a third again as many packets. Cloud determined that by
using the new formula it could produce from the quantity
of Laponite that it had on hand 4.5 million small and 5
million large packets, compared to the 3.8 and 3.9 mil-
lion called for by the February and April orders but not
yet delivered. Cloud had delivered 700,000 of the large
packets ordered in February and April; that is why it had
7.7 million packets still to deliver under those orders
rather than 8.4 million, the total number of packets or-
dered (2.3 + 3.2 + 1.5 +1.4 = 8.4).
   Although it had received no additional purchase orders,
Cloud sent Hasbro an order acknowledgment for 4.5 mil-
lion small and 5 million large packets with a delivery
date similar to that for the April order, but at a lower price
per packet, reflecting the smaller quantity of Laponite,
the expensive ingredient in the powder, in each packet.
   Cloud’s acknowledgment was sent in June. Hasbro did
not respond to it—at least not explicitly. It did receive it,
however. And Kathy Esposito continued having e-mail
exchanges and phone conversations with Cloud. These
focused on delivery dates and, importantly, on the quan-
tities to be delivered on those dates. Importantly because
some very large numbers—much larger than the Feb-
ruary and April numbers, numbers consistent however
with Cloud’s order acknowledgment sent to Hasbro
in June—appear in these and other e-mails written by
her. In two of the e-mails the quantity Cloud is to ship
is described as “more or less depending on the formula,”
consistent with Cloud’s understanding that if the for-
mula reduced the amount of Laponite per packet Cloud
should increase the number of packets it made rather
than return unused Laponite to Southern Clay Products.
A notation made in August by another member of Hasbro’s
6                                               No. 02-1486

purchasing department, Maryann Ricci—“Cloud O/S;
4,000,000 sm; 3.5 million lg.”—indicates her belief that
Cloud had outstanding (“O/S”) purchase orders for 4
million small and 3.5 million large packets. These num-
bers were far in excess of the undelivered portions of
the February and April orders; and since all the earlier
orders had, so far as we can determine, already been
filled and so were no longer outstanding, she must
have been referring to the numbers in Cloud’s June or-
der acknowledgment.
   The district judge, despite ruling for Hasbro, found
that indeed “Hasbro intended to exceed the quantities
of . . . packages it had ordered from Cloud in February and
April of 1996,” that “Hasbro was more concerned with
prompt product than with the specific terms of its order[s],”
and, most important, that “given Hasbro’s repeated message
that it could not get enough Laponite HB to fill its needs
in a timely fashion, Cloud’s decision to produce as many
packets as possible appeared to be a safe course of action.
Cloud was trying to keep pace with Hasbro’s Laponite
HB needs, a task made virtually impossible by the length
of time it took Southern Clay to fill Cloud’s Laponite
HB orders.” The judge even suggested that given Hasbro’s
desperation, Cloud could have persuaded Hasbro to exe-
cute additional purchase orders at prices equal to those
in the February and April orders. Instead, rather than try-
ing to take advantage of Hasbro’s fix, Cloud reduced its
price to reflect its lower cost. A curious consequence of
the reduction, unremarked by the parties, is that even
if Cloud has no contract remedy, it has (unless time barred)
a remedy in quantum meruit for the benefit it conferred
on Hasbro by voluntarily reducing the price specified in
the February and April purchase orders.
 When some months later Hasbro pulled the plug on
Wonder World Aquarium, Cloud had not begun delivering
No. 02-1486                                                 7

any of the additional quantity that it had manufactured
over and above the quantities called for in the February
and April purchase orders.
  Was Cloud commercially unreasonable in producing
the additional quantity without a purchase order? If not,
should the Uniform Commercial Code, which was in-
tended to conform sales law to the customs and usages
of business people, UCC §§ 1-102(2)(b), 1-105 comment 3;
In re Merritt Dredging Co., 

, 206 (4th Cir. 1988);
Kerry Lynn Macintosh, “Liberty, Trade, and the Uniform
Commercial Code: When Should Default Rules Be Based
on Business Practices?” 38 Wm. & Mary L. Rev. 1465, 1488-
91 (1997), nevertheless condemn Cloud, as the district
judge believed, for failing to request written purchase
orders for the additional quantity that the change in for-
mula enabled it to manufacture? Or was Hasbro contrac-
tually obligated to pay for that additional quantity?
  The answer to these questions depends on whether
there was a valid modification of the quantity specifica-
tions in the February and April purchase orders (obvious-
ly Hasbro cannot complain about the price modification!).
The October letter provided that purchase orders could
not be modified without Hasbro’s written consent. Cloud
signed the letter and so became bound by it, considera-
tion being furnished by Hasbro’s continuing to do busi-
ness with Cloud. Hasbro’s order acknowledgments ac-
companying its February and April purchase orders also
provided that the orders could not be modified with-
out Hasbro’s written consent.
  Cloud did not sign Hasbro’s acknowledgments and its
own acknowledgments omitted the provision requiring
that any modification have Hasbro’s written consent. But
these facts have no significance. In the case of discrepant
order and acceptance forms, if the acceptance merely adds
8                                                No. 02-1486

a term, that term binds the offeror, UCC § 2-207(1); this
modification of the common law’s “mirror image” rule
minimizes transaction costs by eliminating a negotiation
over the additional term unless the offeror is unwilling
to accede to the offeree’s desire for it. But what if the term
added by the acceptance contradicts a term in the offer?
Then it doesn’t become a part of the contract—that much
is clear. § 2-207(2)(b). But is there a contract, and if so
what are its terms? The UCC doesn’t say, but the majority
rule, and the rule in Illinois, is that the inconsistent
terms cancel each other out and the court fills the result-
ing void with a term of its own devising. William B. Daven-
port, Daniel R. Murray & Donald R. Cassling, Uniform
Commercial Code with Illinois Code Comments § 5/2-207,
Illinois Code Comment 11, pp. 126-27 (Illinois Practice
Series, vol. 2a, 1997).
   In this case, however, there was neither a supplemental
nor an inconsistent term in the acceptance; there was no
term concerning modification, and in such a situation
Hasbro’s term is enforceable. Earl M. Jorgensen Co. v. Mark
Construction, Inc., 

, 982-83 (Hawaii 1975);
1 James J. White & Robert S. Summers, Uniform Commer-
cial Code 15-16 (4th ed. 1995). It is a case of different but
not inconsistent terms, in which event the acceptance is
effective to make a contract. UCC § 2-207(1). The offeree’s
silence is not interpreted as rejection in this situation
because transaction costs would again be higher if the
offeror had to quiz the offeree on whether every term in
the offer not mentioned in the acceptance was acceptable
to the offeree. Cloud, the offeree, knew that Hasbro wanted
the modification provision and if this was unacceptable
it should have said so.
  For unexpressed reasons the district judge did not
focus on the contractual provisions requiring that any
No. 02-1486                                                 9

modification of a purchase order be in writing. She consid-
ered only whether the UCC’s statute of frauds required
this, and ruled that it did. The quantity term in a contract
for the sale of goods for more than $500 must be memo-
rialized in a writing signed by the party sought to be held
to that term, UCC § 2-201(1), and so, therefore, must a
modification of that term. UCC § 2-209(3). However—and
here we part company with the district judge—Kathy
Esposito’s e-mails, plus the notation that we quoted ear-
lier signed by Maryann Ricci, another member of Hasbro’s
purchasing department, satisfy the statutory requirement.
The UCC does not require that the contract itself be in
writing, only that there be adequate documentary evidence
of its existence and essential terms, which there was here.
Architectural Metal Systems, Inc. v. Consolidated Systems,
Inc., 

, 1229-31 (7th Cir. 1995); Monetti, S.P.A.
v. Anchor Hocking Corp., 

, 1185 (7th Cir. 1991);
Axelson, Inc. v. McEvoy-Willis, 

, 1233 n. 6 (5th
Cir. 1993).
  But what shall we make of the fact that Kathy Esposito’s
e-mails contained no signature? The Electronic Signatures
in Global and National Commerce Act, 15 U.S.C. § 7001,
provides that in all transactions in or affecting interstate
or foreign commerce (the transactions between Cloud and
Hasbro were in interstate commerce and affected both
interstate and foreign commerce), a contract or other rec-
ord relating to the transaction shall not be denied legal
effect merely because it is in electronic form. That would
be conclusive in this case—had the e-mails been sent
after the Act took effect in 2000. But they were sent in
1996. The Act does not purport to be applicable to trans-
actions that occurred before its effective date, and, not
being procedural, compare Landgraf v. USI Film Products,

, 275 (1994), it is presumed not to apply retroac-
tively. Johnson v. Ventra Group, Inc., 

, 745 (6th
10                                                No. 02-1486

Cir. 1999). But like the court in Shattuck v. Klotzbach, No.
011109A, 

, at *2-3 (Mass. Super. Dec. 11,
2001), we conclude without having to rely on the federal
Act that the sender’s name on an e-mail satisfies the sig-
nature requirement of the statute of frauds. Toghiyany v.
AmeriGas Propane, Inc., 

, 1091 (8th Cir. 2002),
another e-mail case that does not cite the electronic sig-
natures act (maybe because, as in this case, the contract
predated the Act), tugs the other way. But it is unclear
whether the court thought the absence of a signature fatal
or thought that it was that absence combined with the
absence of an essential term—the duration of the con-
tract—that triggered the statute of frauds.
   Neither the common law nor the UCC requires a hand-
written signature, Just Pants v. Wagner, 

, 251
(Ill. App. 1993); Monetti, S.P.A. v. Anchor Hocking 

, 931 F.2d at 1182; Hillstrom v. Gosnay, 

, 469
(Mont. 1980); Davenport, Murray & Cassling, supra, § 5/1-
201, Illinois Code Comment 42, pp. 53-54; cf. Restatement
(Second) of Contracts § 134, comment a (1981), even though
such a signature is better evidence of identity than a typed
one. It is not customary, though it is possible, to include an
electronic copy of a handwritten signature in an e-mail, and
therefore its absence does not create a suspicion of for-
gery or other fraud—and anyway an electronic copy of a
signature could be a forgery.
  The purpose of the statute of frauds is to prevent a
contracting party from creating a triable issue concerning
the terms of the contract—or for that matter concerning
whether a contract even exists—on the basis of his say-so
alone. That purpose does not require a handwritten signa-
ture, especially in a case such as this in which there is
other evidence, and not merely say-so evidence, of the
existence of the contract (more precisely, the contract
No. 02-1486                                                  11

modification) besides the writings. The fact that Cloud
produced the additional quantity is pretty powerful evi-
dence of a contract, Consolidation Services, Inc. v. KeyBank
National Ass’n, 

, 821 (7th Cir. 1999); Monetti,
S.P.A. v. Anchor Hocking 

, 931 F.2d at 1183, as
it would have been taking a terrible risk in doing so had
it thought it would have no right to be paid if Hasbro
refused to accept delivery, but would instead be stuck
with a huge quantity of a product that had no salvage
value. Actually, in the case of a contract for goods specially
manufactured by the buyer, partial performance by the
seller takes the contract outside the statute of frauds,
without more. UCC § 2-201(3)(a). This may well be such
a case; but we need not decide.
  The background to the modification—the fact that the
parties had dealt informally with each other (as shown by
their disregard of the form contracts), and above all that
Hasbro plainly wanted more product and wanted it fast—
is further evidence that had Cloud asked for a written
purchase order in June 1996 for the additional quantity,
Hasbro would have given it, especially since Cloud was
offering a lower price.
   There is more: “between merchants [a term that em-
braces ‘any transaction with respect to which both parties
are chargeable with the knowledge or skill of merchants,’
UCC § 2-104(3)] if within a reasonable time a writing
in confirmation of the contract and sufficient against
the sender is received and the party receiving it has rea-
son to know its contents, it satisfies the requirements of
subsection 1 [the statute of frauds] . . . unless written notice
of objection to its contents is given within 10 days after it
is received.” UCC § 2-201(2). Cloud sent an order acknowl-
edgment, reciting the increased quantity, shortly after the
oral modification, and Hasbro did not object within ten
12                                                 No. 02-1486

days. Campbell v. Yokel, 

, 628-31 (Ill. App.
1974); Klockner, Inc. v. Federal Wire Mill Corp., 

,
1374, 1376 (7th Cir. 1981); Apex Oil Co. v. Vanguard Oil &
Service Co., 

, 423 (2d Cir. 1985).
   So Hasbro’s statute of frauds defense fails on a number
of independent grounds. But what of the contractual re-
quirement of the buyer’s consent in writing to any mod-
ification? Could that stiffen the requirements of the UCC’s
statute of frauds? Parties are free to incorporate stronger
conditions for contractual modification than the UCC
provides: “A signed agreement which excludes modification
or rescission except by a signed writing cannot be other-
wise modified or rescinded, but except as between mer-
chants such a requirement on a form supplied by the mer-
chant must be separately signed by the other party.” UCC
§ 2-209(2); see Martinsville Nylon Employees Council Corp.
v. NLRB, 

, 1267 (D.C. Cir. 1992); Wisconsin
Knife Works v. National Metal Crafters, 

, 1292
(7th Cir. 1986) (dissenting opinion); Frank A. Rothermel,
Comment, “Role of Course of Performance and Confirma-
tory Memoranda in Determining the Scope, Operation
and Effect of ‘No Oral Modification’ Clauses,” 48 U. Pitt. L.
Rev. 1239, 1251-52 (1987). The UCC’s statute of frauds
requires only quantity terms to be in writing. The contrac-
tual requirement that the buyer’s consent be in writing
was not limited to quantity terms, but this makes no dif-
ference, since those are the terms in dispute.
  Could the contractual statute of frauds (to speak oxy-
moronically) be broader in a different sense? Specifically,
could “consent in writing” require an explicit written
statement of consent, missing here, rather than merely an
inference of consent from a writing or series of writings?
Maybe, but Hasbro does not argue that the contractual
statute of frauds in this case has any different scope from
No. 02-1486                                                 13

the statutory, though it seems highly unlikely that a no-oral-
modification clause would be subject to the exception in
section 2-201(2) (quoted earlier) to the statute of frauds.
Such a clause is added to a contract when the parties
want to draft their own statute of frauds, as they are per-
mitted to do; and there is no reason to suppose that they
would want to adopt wholesale the limitations that the
UCC imposes on its own statute of frauds. If they wanted
those limitations they wouldn’t need their own, custom-
ized clause.
   So we may set section 2-201(2) to one side. That leaves
intact, however, Cloud’s argument, which we have ac-
cepted, that there was adequate evidence of written con-
sent to the modification. And it leaves intact still another
alternative argument by Cloud: “an attempt at modifica-
tion” that does not satisfy the statute of frauds neverthe-
less “can operate as a waiver.” § 2-209(4). The word “can”
is key. To prevent the “attempt” provision from eviscerat-
ing the statute of frauds, the courts require that the at-
tempting modifier, Cloud in this case, must show either
that it reasonably relied on the other party’s having waived
the requirement of a writing, Wisconsin Knife Works v.
National Metal 

, 781 F.2d at 1286-87 (7th Cir.
1986); American Suzuki Motor Corp. v. Bill Kummer, Inc.,

, 1386 (7th Cir. 1995); contra, BMC Industries,
Inc. v. Barth Industries, Inc., 

, 1333 (11th Cir.
1998), or that the waiver was clear and unequivocal. In
re Nitz, 

, 103 (Ill. App. 2000); Lavelle v.
Dominick’s Finer Foods, Inc., 

, 291-92 (Ill. App.
1992); McElroy v. B.F. Goodrich Co., 

, 724 (7th
Cir. 1996); Bank v. Truck Ins. Exchange, 

, 739 (7th
Cir. 1995). This exception to the statute of frauds applies
equally to the “buyer’s written consent” provision of the
parties’ contracts, UCC § 2-209(4); Wisconsin Knife Works
v. National Metal 

, 781 F.2d at 1284-87, be-
14                                             No. 02-1486

cause waiver is a general doctrine of contract law rather
than an appendage to the statute of frauds.
  The district judge erred by requiring that Cloud show
both reasonable reliance and that the waiver was clear and
unequivocal. There was no clear and unequivocal waiver,
but there was reliance. The judge found reliance. She
found that Cloud had been acting in good faith in produc-
ing the additional quantity of packets because it reason-
ably believed that Hasbro wanted the additional quantity.
But she concluded that Cloud had been unreasonable
in relying on its reasonable belief because it could so
easily have insisted on a written purchase order modifying
the quantity terms in the February and April orders. Rea-
sonableness, however, is relative to commercial practices
and understandings rather than to the desire of judges and
lawyers, reflecting their training and professional culture,
to see a deal memorialized in a form that leaves no room
for misunderstanding the legal consequences. The em-
ployees of Hasbro and Cloud who were responsible for
the administration of the parties’ contractual undertaking
were not lawyers. Doubtless because of this, the parties
had, as we have noted, been casual about documentation.
Cloud had treated the purchase orders as sources of in-
formation on how much Hasbro wanted when and ac-
cording to what formula, but had paid no attention to
them as contracts containing terms and conditions that
might bind it. Hasbro had treated Cloud’s purchase-order
acknowledgments with similar insouciance. The parties
had a smooth working relationship the details of which
were worked out in informal communications. With time
of the essence and the parties on good terms and there-
fore careless or impatient with formalities, Cloud was
reasonable in believing that if Hasbro didn’t want to be
committed to buying the additional quantity that it plainly
wanted in the summer and autumn of 1996, it would so
No. 02-1486                                               15

advise Cloud rather than leading Cloud down the prim-
rose path. A practice, under the rubric of “course of deal-
ing,” can be evidence of what a contract requires, see, e.g.,
UCC § 1-205; Restatement (Second) of Contracts § 223 (1981);
Frank Novak & Sons, Inc. v. Sommer & Maca Industries, Inc.,

, 703-05 (Ill. App. 1989)—can even, under
the rubric of “contract implied in fact,” give rise to bind-
ing contractual obligations though no words are spoken.
Brines v. XTRA Corp., 

, 703 (7th Cir. 2002).
  Cloud could have been more careful. But a failure to insist
that every i be dotted and t crossed is not the same thing
as being unreasonable. In any event, to repeat an earlier
point, Hasbro did give its written consent to the modifica-
tion.
  We conclude that the June modification was enforce-
able and we therefore reverse the judgment and remand
the case for a determination of Cloud’s damages.
                                 REVERSED AND REMANDED.

A true Copy:
       Teste:

                          _____________________________
                          Clerk of the United States Court of
                            Appeals for the Seventh Circuit




                   USCA-02-C-0072—12-26-02