Hello everyone. I will be talking in this module about working days versus calendar dates. Why they are different, as a scheduler, why it's important to understand the differentiation between both. So let's start the module here. Contractual terms almost universally specify calendar days for time sensitivity issues. Such as, let's say, projects duration, or project finish date, or mobilization after the notice to proceed for construction from the client to the contractor. Some finished deadlines for activities or major milestones that you do have in your project, and so on. So you would need to better understand the differences between calendar dates and working day to deal with this time sensitivity issues. Some companies, contractors, or subcontractors claim that they do not work on specific dates, or holidays versus other holidays. For example, some companies, you can find them working in a flag day, or memorial day, and others they do not work in these holidays. some companies, they do not work on 4th of July, others say, no, we do work in 4th of July. And of course country by country, it's different from geographical locations. Therefore, we do not include the holiday assigned by these companies to the working days of the project. We do not assign these holiday's, and we will go through an example later. The same apply to the client, to the owner of the project, sometimes a contractor can work in a specific holidays, the client does not. Because of this potential confusion that may arise during the project, during the construction of the project, usually this be avoided from the beginning when you develop the schedule by specifying durations and deadlines in calendar dates from day one, from the beginning of the project. The simplest way to go through this is to relate the project's working days to the calendar dates. So the first step in this case, you would then need to assign that first calendar date as working day number one, or WD1. So moving forward with the count on the calendar dates from the working days, the non-working days, such as holidays or could be even weekends, will not be added to the count on the calendar dates. Like the following example here. So as we can see, the contractor, let's say say this is December 20th, a calendar showing from December 20th, 21, 22, all the way to January 1st, and on finalizing just a piece of the calendar on January 9 here. Just like small project, and as you can see here, the contractor starts that project on December 22nd here, on a Tuesday. So the first working day of the project, and we refer to it as WD1, working day number one, WD2, WD3, and so on. For this project, for example, we do have how many working days? We do have 12 working days. It's a smaller project, it will end on working day number 12, which will be in calendar date, January 8, Friday. Also if you notice the contractor from this calendar, agreed with the client to not work on December 25, as we can see here, there is no working day. We notice we have a working day number one on the 22nd, number two on the 23rd, working day number three on the 24th and then a holiday on the 25. And the we jump to working day number four, that means the client agrees with the contractor that they will not do any work also on weekends. Here in the US, the weekend start on the Saturday and the Sunday, other parts of the world you might have a different weekend days. For example, in Middle East, you find some of the contractors they don't work on Friday and Saturday, and the start day of the week would be on Sunday. This is very important to understand when you are in an international company dealing with the global projects, even if you with the company and have the project overseas. You'll meet on the understand what's going on overseas from the working days, the weekends, the holidays, or if you are at the same country, the US China, India and so on, what are the holidays and weekends, refer to in that country. In this specific example, as I mentioned, that December 25 they've agreed not to work, the weekends, Saturday and Sunday, if you notice I highlight it in yellow here. We do not work and also in January 2nd, I'm sorry, in January 1st, the agreement, the contractual term that there is no work. So if you notice in January 1st, the day before is working day number seven and then the working day number eight, the next working day, we will skip January 1, January 2, January 3, and proceed with the construction or the work on January 4th as the workday number eight. And move forward towards the end of the week until Friday which is the last day of that project as a working day. So you also have to know, in addition to the geographical constraints that I just mentioned, that not all contractors, or in a matter of fact, not also all clients and owners have the same assigned holidays. So you have to understand from day one all these terms before you proceed, so as insensitivity issues, you will deal with it from day one. It's very important from the planning and scheduling point of view. So let's do an example, so we can understand this in more details with numbers and some calculations.