0 Rules for constructing Identifier names

1.A variable name is any combination of 1 to 31 alphabets,digits or underscores. Some compilers allow  variable names whose length could be up to 247 characters. Still, it would be safer to stick to the rule of 31 characters. Do not create unnecessarily long variable names as it adds to your typing effort.

2.The first character in the variable name must be an alphabet or underscore.

3.No commas or blanks are allowed within a variable name.

4.No special symbol other than an underscore (as in gross_sal) can be used in a variable name.