Create link to other sections in the document which shows the tartget text

I’m creating an official document in writer and need to reference other sections. For example ‘this thing must conform to something defined in section 5.a.’
except as its a new document section 5.a is likely to change as more sections are added and the automatic numbering system chages it. So it might become section 6.b. so I need to text on the link to change. so it then reads ‘this thing must conform to something defined in section 6.b.’
I hope someone can help me here as I will likely get very confused and/or forget to change one of the links if i have to do it by hand.

Sorry if I’m not very good at explaining myself but I hope someone understands me.

Hello Macknade,

1) First select your field where it says "section 5.a", and choose the menu "Insert : Cross-Reference..."
2) in the listbox called "Type", select the item "Set Reference", and type a suitable name for this reference, e.g. "My Ref 1"
3) Back in your document, go to the line where it says "this thing must conform to something defined in section 5.a.", and select the part "section 5.a",
4) Then again choose the menu "Insert : Cross-Reference...",
5) in the listbox called "Type", this time select the item "Insert Reference", 
6) in the listbox called "Insert reference to", select the item "Reference", 
7) in the listbox called "Selection", select the item you just created, e.g. "My Ref 1". 
8) Then click on the "Insert" button and Close

Couldn’t figure out how to set text of link with this method; just got a hidden field…

If 5.a is the section number, then do not write it manually but use Insert > Cross Reference. In list Type select Headings, in the list Selection select the heading of section 5.a and in list Insert reference to select Number (full context). Headings are automatically available as link target, without the need to define a reference.