is clicked.A Mix Design Form is used for entering the data for a mix and one is displayed when Firstmix is started.
Before using the Mix Design Form you should have an understanding of the Specification of a Concrete Mix and of the Mix Design Procedure used in Firstmix and be aware of Firstmix Limitations.
You should also ensure that the program Settings which control the units, methods of testing concrete strength and measuring workability and other options for the mix design, suit your requirements.
A Mix Design Form is in Windows terminology a view on a document. The view is the Mix Design Form you see on the screen and the document is the mix file. It is possible to have several mix files open simultaneously when Firstmix is run, but only one file will be active at any one time. This will be the file, which is displayed in a Mix Design Form whose Title Bar appears in full colour. The name of the active file is displayed on the Firstmix Title Bar. The Mix Design Form which appears at the start of the program will normally display a new mix file, which will not yet have a name, and so ‘Unnamed” is shown on the Firstmix title bar.
As soon as you have entered one item of data, the mix quantities, which are displayed at the end of the form, will be calculated. In fact mix quantities are calculated and all form fields are updated, whenever:
is clicked.The form can be split with the split box situated above the right scrollbar, so that input data and mix quantities can be viewed together and compared. Alternatively you can bring up a second window in which to view the form with the New Window item of the Window menu.
The mix quantities are calculated in five mix design stages. The stages are indicated on the form by Roman numerals. You can use context help to get an explanation of what each stage does by clicking with the mouse on the Roman numeral for the stage or on the background of the area of the form which deals with the stage. You can also get help about any item on the form by clicking on it. Context Help may be initiated by clicking the 
icon on the toolbar with the mouse.
On the Mix Design Form fields in which data should be entered have a double border and their contents appear in bold type as below.
Other fields contain values, which cannot be edited. These are either derived values or intermediate results. They are displayed, so that the basis of the mix design is clear and errors will be more obvious. These fields have a single border and their contents appear in normal type as below.
Many fields require data to be entered in some circumstances but are read-only in other circumstances.
The TAB key or the Next Field item of the Edit Menu can be used to advance the cursor to next field in the current mix design form. Alternatively you can click with the mouse in the field where you wish to enter data.
If invalid data items have been entered, the Mix Quantities at the end of the form will be output as zeros. The error(s) will be listed in the Messages window, which is most easily viewed by clicking the 
icon on the toolbar. The Messages window contains Errors, Warnings and Notes and should be checked at regular intervals, and certainly before saving or printing a mix design.
When you have completed a satisfactory mix design, you should save the contents of the mix design form, including aggregate measurements and/or trial mix results if these have been used in the mix design, as a mix file, so that the mix design is not lost. You can also print the contents of the mix design form. If aggregate measurements and/or trial mix results have been used in the current mix design, they may also be printed and Company and Job Details can be included.