credit commitments the table below summarizes citigroup 2019s other commitments as of december 31 , 2008 and december 31 , 2007 . in millions of dollars u.s . outside december 31 , december 31 .
what percentage of citigroup 2019s total other commitments as of december 31 , 2008 are comprised of credit card lines?
the majority of unused commitments are contingent upon customers 2019 maintaining specific credit standards . commercial commitments generally have floating interest rates and fixed expiration dates and may require payment of fees . such fees ( net of certain direct costs ) are deferred and , upon exercise of the commitment , amortized over the life of the loan or , if exercise is deemed remote , amortized over the commitment period . commercial and similar letters of credit a commercial letter of credit is an instrument by which citigroup substitutes its credit for that of a customer to enable the customer to finance the purchase of goods or to incur other commitments . citigroup issues a letter on behalf of its client to a supplier and agrees to pay the supplier upon presentation of documentary evidence that the supplier has performed in accordance with the terms of the letter of credit . when drawn , the customer then is required to reimburse citigroup . one- to four-family residential mortgages a one- to four-family residential mortgage commitment is a written confirmation from citigroup to a seller of a property that the bank will advance the specified sums enabling the buyer to complete the purchase . revolving open-end loans secured by one- to four-family residential properties revolving open-end loans secured by one- to four-family residential properties are essentially home equity lines of credit . a home equity line of credit is a loan secured by a primary residence or second home to the extent of the excess of fair market value over the debt outstanding for the first mortgage . commercial real estate , construction and land development commercial real estate , construction and land development include unused portions of commitments to extend credit for the purpose of financing commercial and multifamily residential properties as well as land development projects . both secured-by-real-estate and unsecured commitments are included in this line . in addition , undistributed loan proceeds , where there is an obligation to advance for construction progress , payments are also included in this line . however , this line only includes those extensions of credit that once funded will be classified as loans on the consolidated balance sheet . credit card lines citigroup provides credit to customers by issuing credit cards . the credit card lines are unconditionally cancellable by the issuer . commercial and other consumer loan commitments commercial and other consumer loan commitments include commercial commitments to make or purchase loans , to purchase third-party receivables and to provide note issuance or revolving underwriting facilities . amounts include $ 140 billion and $ 259 billion with an original maturity of less than one year at december 31 , 2008 and december 31 , 2007 , respectively . in addition , included in this line item are highly leveraged financing commitments which are agreements that provide funding to a borrower with higher levels of debt ( measured by the ratio of debt capital to equity capital of the borrower ) than is generally considered normal for other companies . this type of financing is commonly employed in corporate acquisitions , management buy-outs and similar transactions. .