In flyng stars, there are scripts that must be read. How applicable is one thing. There are still some useful information to add to knowledge.
Over the period, I'll drop some pointers here and there. Hope you may benefit or clarify in your studies or application.
不知来路，焉知入路，盘中八卦皆空
There are many different commentaries from different authors and interpreters. Some try to base on that author's thinking or period of understanding to explain. Some relate to the source scripts to explain. Other authors explain according to "that" situation or base on flying stars only.
Generally, it means if you don't know the bigger picture, the forthcoming "activator", the road that leads to your spot, then there's no point to know or talk about the entrance or entry point. If it is not known or made to connect, then the whole plot become meaningless.
With the above phrase, whether accurately to mean the dragon veins or any literally featured path, it can be used accordingly to the circumstances.
Some explain with reference to 城门决 and 来脈， disagreeing the emphasis on facing and sitting. Some explain that 来路是各运／天盘， 入路指山， to explain that if you don't know the period or incoming star, then you won't know the placements of the mountians etc, making the plot redundant.
Both has some truths applicable on their own. To accurately explain the meaning, then you have to base on that era where the author wrote, his foundation of knowledge. So the answer is very simple. No need to argue/ debate on each other's interpretation. Remember, this is an author writings.
The main part of having the understanding is this:
Once you establish 太极, if you don't know how to see what star is coming, what features out there, "road" can mean the pathway or dragon vein or the water direction, then the whole setup become meaningless and not applicable as the meanings within become mixed/ messy/empty.
So similarly in 雪心赋： 入山寻水口，登穴看明堂. If want to establish a spot, you should find the water cross point (junction/ mouth/ exit/ incoming) or look at the space in frontage/ facing. Flying stars application is in conjunction to this. When people in any country, want to establish a site to build homes, it is always natural to look for the water source. Nobody will want to build home in Sahara desert unless there are man made ready.
Writing until here, students or learners with common sense will be able to correlate into different situations. Don't just stand inside the house and start plotting the stars allocation. If the "incoming" road doesn't lead to the house door, no point. If the exterior formation doesn't conform, no point.
By this "incoming road", its another knowledge. Note: its not "oncoming" road (for those new practioners).
In 玄機赋：阴阳虽云四路，宗支只有两家
Some interpret as 1234 and 6789. Some interpret as facing, sitting, 天盘 (stars)，地盘 (directions/plot/earth). Ultimately its still 阴阳吉凶动静。 If like to be more relevant, then you have to read the knowledge of the writer at that time. It was referring to stars auspicious and inauspicious all the time. The principle of yin and yang never fails in any writing. So if your roots are not firm, then any understanding may misinterpret.
When read further , 九曜吉凶，悔吝斯章, you should understand that this is drawn from the very basics. If you can't derive from the above 8 words its origin, then you have a long way to go. It is no point for me to discuss this as every practitioner need to go through the basics. Once you do not recognise its the basic, any further discussion here will be back to basics.
**With reference to "盘中八卦皆空“, is very simple. 地盘静，天盘动。 天盘不动就不用知来路， 那地盘自然“皆空”。 Understand?
Many practitioner straight away jump to flying the stars. See water star 8 in the facing, usually deduce as auspicious and try to activate with water etc. This is too superficial. Practioner need to understand 地天人元龙 application as well. 8 facing star not necessary works positively :) Sometimes it may cause problems instead.
The writings here are mainly for people who know the basics. If you do not, then there are books, courses, teaching you the basics. If you practise and get stuck somewhere, probably here can enlighten you. I'm not a writer, so don't expect detailed explanations.
Feng shui faction is broadly into 2 catergories: 飞星派 与三合派。If you are basing on 沈竹礽 writitngs, then you need to understand he died before completing and was compiled by his son and fellowship. Also you need to know that he learned/ reference from 蒋大鸿, 章仲山.
Why do you need to know this? For example, I gathered all my experience all in papers or data, my own family members/ others won't know or fully understand everything I know/ wrote/ scribbled and /or translate to my exact knowledge and experience. Therefore you need to give it a pinch of salt. 蒋大鸿 is famous for singng songs, so if you read his writings, you confuse yourself if you don't have any experience or basics. Although 沈 has partially interpreted but his scripts is self-interpreted and also wrote was without punctuation. Your head will grow big. No doubt some masters have attempted to make a commentary out, it is still based on their perspective. So all these studies will lead you to learn and unravel one after another probably on a bias basis.
Read Flying start part 2