Try to Script CREATE on table Northwind..Employees on Sybase ASE 15 [10.168.11.46].  I get the below which has an empty constraint :

CREATE TABLE dbo.Employees  (
    EmployeeID         int IDENTITY NOT NULL,
    LastName           nvarchar(20) NOT NULL,
    FirstName          nvarchar(10) NOT NULL,
    Title              nvarchar(30) NULL,
    TitleOfCourtesy    nvarchar(25) NULL,
    BirthDate          datetime NULL,
    HireDate           datetime NULL,
    Address            nvarchar(60) NULL,
    City               nvarchar(15) NULL,
    Region             nvarchar(15) NULL,
    PostalCode         nvarchar(10) NULL,
    Country            nvarchar(15) NULL,
    HomePhone          nvarchar(24) NULL,
    Extension          nvarchar(4) NULL,
    Photo              image NULL,
    Notes              text NULL,
    ReportsTo          int NULL,
    PhotoPath          nvarchar(255) NULL,
    CONSTRAINT PK_Employees PRIMARY KEY CLUSTERED(EmployeeID)
    WITH max_rows_per_page = 0, reservepagegap = 0
    )
LOCK ALLPAGES
GO
ALTER TABLE dbo.Employees
    ADD CONSTRAINT UQ_multi
    UNIQUE (EmployeeID, LastName, FirstName)
    WITH max_rows_per_page = 0, reservepagegap = 0
GO
ALTER TABLE dbo.Employees
    ADD CONSTRAINT "
GO
ALTER TABLE dbo.Employees
    ADD CONSTRAINT FK_IEG_TEST
    FOREIGN KEY(EmployeeID, LastName, FirstName)
    REFERENCES dbo.Employees_ref(EID, LN, FN)
GO
ALTER TABLE dbo.Employees
    ADD CONSTRAINT FK_Employees_Employees
    FOREIGN KEY(ReportsTo)
    REFERENCES dbo.Employees(EmployeeID)
GO